MechMate CNC Router Forum

Go Back   MechMate CNC Router Forum > Common Assemblies & Parts > Driving Mechanisms: Rack/pinion, gears, screws, belts & chains
Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Reply
 
Thread Tools
  #31  
Old Wed 06 June 2007, 06:31
Marc Shlaes
Just call me: Marc
 
Cleveland, OH
United States of America
Send a message via Skype™ to Marc Shlaes
I'm confused

My build is still in the planning stages. But that is how I work. I think a lot about what I am going to do before I start. Now here is the question. For a new builder, should I even be reading this stuff on belt drives or should I just plan on buying geared motors? Is this information primarily for retrofits or are there pros and cons to belt drives vs. geared motors? Is the price difference the driving factor? Oh, one other question, where are the US builders buying there Oriental motors?


Thanks.

Marc
Reply With Quote
  #32  
Old Wed 06 June 2007, 07:30
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Last question first: I'm sure that the US builders buy their OM's direct from OM. (The link is in the motors thread). Even I bought them direct and had them delivered to a friend in the US who on-shipped them to me. Buying from OM with a credit card was the easiest purchase, with the fastest delivery, that I ever had.

The issue on which motor/belt/box combo is best, is largely driven by price vs. resolution vs. effort (nobody has mentioned space yet - the gears/belts make the gantry a bit longer and hits you in the stomach a bit more.)

Lowest price, effort & resolution is a direct drive non-OM motor at around $100 each in the US and $50 in China. Most of us are reading this thread because we are tempted to start cheap & easy and then see if we need to add some (belt) reduction to the motor at a later stage.

Top price, with lowest effort and highest resolution are the geared Oriental Motors at $257 each in the US and quite a bit higher in the rest of the world because of agents or transport.

Experimenting with retrofitting belts could even be the most expensive option if you have to find outsiders to do all the machining for you.

I would venture to say that most people who have direct motors on their CNC routers have been happy to accept them as they are, and that they might only have a passing interest in spending some effort and money to get a better resolution.
Reply With Quote
  #33  
Old Wed 06 June 2007, 08:23
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
My goal for attaching the belt transmission was to reduce 'chatter'. The factory 'resolution' on my Shopbot PRT-Alpha was about 0.00314" per step. (20 tooth gears with a 1" pitch diameter. 1,000 steps per shaft revolution. Using the same pinion gear with a Gecko driven stepper would have given about 0.00157" per step due to the 2,000 steps per revolution of the Gecko.) When I added the belt drive transmission, I had to change the steps-per-revolution to 500, which gave me about 0.0021" per step with the 1:3 ration belt-drive. However, the belt-drive virtually eliminated the 'chatter'. My theory is that the 3X increase in torque helps hold the off-axis motors in position. Whatever is happening, the belt-drives cured the problem. As Gerald pointed out, the belt-drive is bulky and costly. Parts cost about $200 to $750 for three drives depending on whether you do your own milling or have a local shop mill the bearing pockets.

The Oriental Motors PK296 motor with either the 1:3.6 gearbox or the 1:7.2 gearbox would be ready to go right out of the box. (I have four of the PK296B2A-SG3.6 motors that will be installed in my next project.)
Reply With Quote
  #34  
Old Wed 06 June 2007, 11:17
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Just to avoid any misunderstanding, Mike was getting 'chatter' even along straight orthogonal cuts, when only one axis was running. In other words, the the holding axis wasn't doing a good job of a fixed position. That issue seems peculiar to the "Alpha" motors which had a local closed-loop control, and which may have been "hunting". His gear ratio change cured those chatters. As he says, probably because of the extra torque - his resolution ended up with 500 steps/motorrev being 1500 steps/pinionrev.

But, with standard old steppers, they do a good job of holding the stopped axis in a fixed position. Where we do see some "chatter" is when one axis is stepping at a certain speed ratio to the other axis. On curves and circles there are short distances where "chatter" (resonance) can be seen and heard when cutting fairly fast. On direct drive we will have 2000 steps/pinionrev - actually a finer resolution than Mike's 1500 steps/pinionrev.
Reply With Quote
  #35  
Old Wed 06 June 2007, 11:37
Marc Shlaes
Just call me: Marc
 
Cleveland, OH
United States of America
Send a message via Skype™ to Marc Shlaes
Thanks tons!

These last posts helped me understand a lot but... Gerald, your last post made me think that new non-geared steppers are just fine. The problem I see is that if I buy non-geared steppers and then am not satisfied with cut quality, I either buy new geared motors or fabricate belt-drives. Shouldn't I just avoid the whole problem and buy geared motors? I understand that they are significantly more expensive but I want to end up with a machine that does what I want. In the overall scheme of life and overall cost of the machine, the price difference seams reasonable. If geared motors are complete overkill on the MechMate (as opposed to the Alpha), then spending the money is dumb. Thanks for further advice.

Marc
Reply With Quote
  #36  
Old Wed 06 June 2007, 12:43
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Have a look at the first post in the motors thread here. If I lived in the US, I would use the geared motors for my next MechMate. Not because they are necessarily so good, but because I am so curious! By all accounts the extra $50 dollars per axis is extremely good value for money, and nobody is suggesting that it might be an overkill - nowhere near it.

However, on the other side, a direct-driven MechMate is also a very useful (profit-making) machine - one learns to live with the occasional little chatters on some cuts when pushing it hard. I've always known that I could add belt boxes to our 2 MechMates, and that I am well-equipped to do it easily and cheaply, but then I think there are more important things to look at first. (like a vacuum table). I initially went direct-drive because our ShopBot was like that. I say again, if I had to start all over, I would probably be getting those 7.2:1 ratio geared motors.
Reply With Quote
  #37  
Old Wed 06 June 2007, 12:52
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Marc,
There are some minor problems with the Oriental Motor's PK296A1A-SG3.6 and SG7.2 geared motors. The main problem is that the gearbox limits torque to about 320 oz*in for the 1:3.6 gearbox and about 2X that for the 1:7.2 gearbox. (I assume that you could push the gearbox harder but with greater wear and possible damage to the gears.) The other problem is that the SG gearboxes have some backlash. Backlash may or may not be a problem depending on what kind of work you do.

Why not ask someone to make some sample cuts for you in the kind of material that you will be cutting? If someone with geared motors cuts the part(s) and someone with non-geared motors cuts the part(s), you'll have side-by-side comparison. The cost to do that should be minimal and then you would have peace of mind. (That's exactly what I should have done before buying the PRT-Alpha. As much as I like the machine now, it took the better part of two years to adjust/modify the machine before I was satisfied.)
Reply With Quote
  #38  
Old Tue 04 December 2007, 09:47
zetacnc
Just call me: Fabio
 
Atibaia
Brazil
Hello all,

These are photos taken this weekend - the machine is ready to rock with all the belt reduction installed and tested.

It's soon to say but the best thing I discovered was the VFD inside panel did not interfered in any moment with the drivers...

The spindle motor became quite hot after 30 minutes running at 12000 rpm when was doing ligth cuts to experiment, and this week will talk to the manufacturer about this, but it proved to be very powerfull...

The maximum velocity reached 21 meters/minute (830 in/minute), but i limited to near 15 meters/minute (590 in/minute)

I hope you enjoy...
Attached Images
File Type: jpg IMG_4681.JPG (51.0 KB, 3929 views)
File Type: jpg IMG_4682.JPG (41.5 KB, 3913 views)
File Type: jpg IMG_4685.JPG (37.3 KB, 4130 views)
File Type: jpg IMG_4686.JPG (35.4 KB, 3898 views)
Reply With Quote
  #39  
Old Sun 30 December 2007, 16:12
larry1larry
Just call me: larry
 
toronto
Canada
I'm gunna get backlashing

I will probably get a lot of backlash on this idea,but only from the members.
You guys will probably"give me the gears"besides the "lashing"OK I am ready,got my helmet on.
For gear reduction why not use spur gears,rather than belts and pulleys?May be much more compact.8Teeth and 40Teeth will give 5 to 1.Rather than elaborate and confirm my lack of knowledge,I ask for the expert advice of the forum.
Larry
Reply With Quote
  #40  
Old Sun 30 December 2007, 17:16
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
Send a message via Skype™ to J.R. Hatcher
I was thinking if you could spring load the gears together like we do the rack and pinion how could it have backlash.
Reply With Quote
  #41  
Old Sun 30 December 2007, 22:44
Bill McGuire
Just call me: Bill
 
Weiser, Idaho
United States of America
Apparently, the oriental motor guys thought gears was a good way to go...since they are selling them, and I for one will be purchasing four of them...

One concern I do seem to recall in a post several months ago is that the angle of the motor (or gears or belts, I suppose) needs to be somewhat perpendicular in relation to the racks... but I could be wrong... not the first time this year either... and there's still one more day left for many more mistakes...
Bill
Reply With Quote
  #42  
Old Mon 31 December 2007, 07:25
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Larry,

Maybe I'm misunderstanding your question. Why would you build a gear reduction using gears when you can buy a stepper motor with a gear box made specifically for it from Oriental Motors? I guess you might save a little bit of money if you were lucky but I don't believe your creation would be nearly as reliable or as accurate as the factory product.
Reply With Quote
  #43  
Old Mon 31 December 2007, 15:34
Charlie
Just call me: Charlie
 
UT
United States of America
The 7.2 and 3.6 from oriental are getting reports of looseing steps due to the gear box binding from workload. I just bought four 7.2's and I want torque, so we shall see. Mike is saying dont ask to much of them because the gearbox strains/binds under load. Plus they are the smaller motor. Mike is useing 600oz*in motor with a 3to1 belt that transfers full torque. 600X3=1800oz*in
If the OM 7.2 gearbox can only handle 640oz*in of torque you dont get your full 300X7.2=2160oz*in transfered to the pinion. In fact you only beat Mike's direct larger stepper by 40oz*in. That also means that you can only use 89oz*in of the motors 300 rating. It just doesnt sound right. Like I said I own four of them(7.2's), building the 4'X8' Mamba and want torque so we shall see whats up with em. Plus I am fortunate enough to live in the same town as Mike. So with his trusted word and my sacrificial motors and full Mamba setup I trust we will get to the bottom of it.

Does all that sound about right Mike? Or at least close

Edit: As Bill said maybe its the angle of the mount that is giving some people problems. Or maybe other parts of the gantry are binding due the new found torque with3.6's or 7.2's on old shopbots? At this point I am still only guessing.

Last edited by Charlie; Mon 31 December 2007 at 15:43..
Reply With Quote
  #44  
Old Mon 31 December 2007, 17:00
larry1larry
Just call me: larry
 
toronto
Canada
Bill & Doug,
My first post here was in Selecting motors thread and noticed the gear motors had less torque than the un geared motors.Orential motors are very expensive compared to others.When a geared version is only $57 more I ask what kind of gear box are you getting.Other gear heads are $600+from other sources.
From reading Mike's post and Charlie's post,I thought the general consensus or at least in my mind it is preferable to direct drive with a larger motor and or gearbox.
This means for some real performance I am back to belt drive.How does one get 7 or 10 to one without a bulky package or two stages?3to1 is max for two pulleys.I thought actually using the pinion gears as gears it may be possible to get higher ratios in a smaller package.
Happy New Year
Larry
Reply With Quote
  #45  
Old Tue 01 January 2008, 09:51
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
I hope that I haven't started a panic about motors and gearboxes. Let's go over the things that we can gleen from the data sheets.

- The PK296A2A-SG3.6 motor has about 320 oz*in permissible torque.

- The PK296A2A-SG7.2 motor has about 720 oz*in permissible torque.

- The PK299-01A motor (no gearbox) has about 800 oz*in holding torque when wired bipolar series and about 550 oz*in holding torque when wired half-coil.

Those are the basic numbers that Oriental Motor publishes. You'll note that the PK299 motor without a gearbox and the PK296A2A-SG7.2 both put out similar torque, depending on how the PK299 motor is wired. So, the speeds that Gerald is getting with his PK299 equipped MechMate would be very similar to the speeds that you should expect with the PK296A2A-SG7.2 equipped MechMate. The main difference is that the 7.2:1 gearbox would give you 7.2X better resolution, but would also require a pulse train 7.2X faster than the non-gearbox motor.

All of the e-mails that I've received where people are having problems with the PK296 sized motors are NON-MechMate machines. As we all know, Gerald has done an excellent job of designing the MechMate, including the use of larger V-rollers for smoother operation and the use of welds and bracing to reduce or eliminate machine flexing. So, the problems that I've been reading about MAY never be seen with the MechMate.

IF you're building a machine that MUST run as fast as possible, you'll PROBABLY want to look at large motors with a belt-drive transmission. A single-stage belt-drive transmission will have a maximum of 3.6:1 reduction. That is the result of the fact that the smallest pulley that can be bored out to accept a 1/2-inch motor shaft is the 20-tooth XL pulley. The largest pulley readily available is a 72-tooth pulley. The math shows that 72 / 20 = 3.6. I can't imagine a 3.6:1 belt-drive transmission being a problem. With a 30-tooth spur gear, the resolution would be 30 / 20 X 3.14159 / 3.6 / 2000 = 0.000654 inches per step. That is 5X finer than the thickness of a piece of copy paper. Believe me when I tell you that you will never get resolution anywhere near 0.0006 inches on any CNC router when you're cutting wood. Wood changes size from minute to minute in my unheated shop - especially as the humidity shifts from the deseret-like dryness to near tropical monsoon-like wetness in August. With a 3.6:1 belt-drive transmission and a PK299-F4.5 motor wired parallel, you'll get more than 2,500 oz*in of torque. The XL belt will probably be the limiting factor with that motor (although I haven't had any problems with XL belts on my 3:1 belt-drive setup).

If you already have 7.2:1 motors, use them. Cut thousands and thousands and thousands of parts with them. By the time that you've worn them out, you'll have both the experience and the money to buy whatever type of motor and gearbox that best suits your needs.
Reply With Quote
  #46  
Old Wed 02 January 2008, 03:28
BernardR
Just call me: Bernard
 
Georgetown Texas
United States of America
DIY Pulley calculation to fabricate T5 pulleys.

I recently joined this forum as I am contemplating building a router / Plasma cutter. My previous experience was converting a Bridgeport size import to 4 axis control using servos, driven by Geckos and Mach2.

Being a Brit and growing in an environment where hobby activities were possible only by doing as much DIY work as possible, I soon found that in 2001 there was comparatively little advice available on motor sizes and gearing ratios and that larger size pulleys were often very difficult to obtain and fairly pricey. I investigated and measuring a variety of pulleys found a couple of constants that enabled any size pulley to be fabricated.

(I just noticed in reviewing the word version of the AutoCad drawing that I just gave the diameter. It is calculated as PD - 0.839= 94.653, Published data = 94.65.)

Currently having drilled the center hole I mount the blank on an arbor and then drill the peripheral holes using a rotary table. However it is also possible to mount the blank and use a standard G-code program to drill the holes, this ability will be dependent on the accuracy of your system.

I have found that there is no real standard for either the pulleys or the belts for T5, some pulleys are obviously machined with a hob as per normal gears but there are others that appear to been drilled and after cutting to the Outer Diameter both sides of the cut holes are edge releaved. It is a similar story with the belts, some have chamfered teeth and slight gearing depth while others are very deep with virtually parallel teeth blending to a radius. Both combinations appear to work equally well together and in the intervening years have not had a broken or damaged belt.

I prepared an AutoCad drawing of a T5-60 tooth pulley. The reason for this size was because it was the largest that I could obtain Manufacturers data, for those interested it will be seen that the nominal Pitch Diameter is easily caclulated, though it is only used to establish the remaining critical dimensions.

On a different subject, I have noted that several people have discussed jerky movement and less than optimum performance. For those users that are interested I submitted some information that may be of interested in looking at ArtSoft's work in this direction, where they have been delving into these problems, the subject heading is: Quantum, long term software solution?

Hopefully some of the data that I have shown may be of some use to you.
Attached Files
File Type: doc T5-60ToothPulley.doc (56.5 KB, 499 views)
Reply With Quote
  #47  
Old Wed 02 January 2008, 04:20
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
Send a message via Skype™ to J.R. Hatcher
When I was considering making a belt reduction I was going to use the parts from a craftsman 3 X 21 belt sander. They were very cheap and only needed slight mods. If anyone is interested I think I could find the model # and post it.
Reply With Quote
  #48  
Old Thu 03 January 2008, 00:40
BernardR
Just call me: Bernard
 
Georgetown Texas
United States of America
Bonding pulleys with Loctite

In reading through the various posts I have noted a couple of times that mention has been made of being limited to a minimum of 20 teeth for a 14mm shaft and I would comment as follows:

It is increasingly common that pulleys and pinions are bonded to shafts without any form of mechanical fastening. Loctite 609 is a classified as a general purpose retaining compound and is good to retain from press fit to up to 5 thou clearance. When the parts are properly degreased and Primed with 7649 strengths over 2,200 psi are attained.

I regularly use this product if I need to do turning operations on a previously completed part and then release the parts by applying a small propane torch to raise the local temperature above 170c.

Examining the xl profile the inner diameter of the teeth is 0.125" less than the outer diameter. Subtracting the 14mm shaft = 0.5512" diameter and using a 16 tooth pulley with a published OD of 0.999" and an inner tooth diameter of 0.874 - .5512 = 0.3028", i.e. a wall thickness of 0.15" which is more than adequate.
I used this method when working on the gearing of the knee (Z) axis of my mill.

The link to Loctite 609 data sheet is: https://tds.us.henkel.com//NA/UT/HNAUTTDS.nsf/web/3E906D6B842166B0882571870000D855/$File/609-EN.pdf
609-EN.pdf (application/pdf Object).

Depending on distributor a small bottle of 609 is in the region of $US12 and the Primer 7649 around $14.

Hope this info is of some use.
Reply With Quote
  #49  
Old Fri 28 March 2008, 13:28
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
Send a message via Yahoo to Robert M Send a message via Skype™ to Robert M
Gear info ?!



Hi Fabio,

May I be audacious and ask you to tell/share more on the how you did & conceive you motor gear belt reduction system ?
I’ve gone through your personal pages, read post 3, got the pics from #1 & #19 but for me, I’m still in the dark as to how you built them ! Never done any but would very much like to give it a try. I’m daring to ask “Better yet, any plans & parts list ? “

From what I can understand there are some advantages to make your own “gear system” vs buying one that is part of the motor as many do to keep it simple The KISS approach !!!
I‘ve read many sources say it can be an advantage & flexible if ever needing for some better resolution or speed !!
But, with this in mind, I can’t seem to see how you kept it all in a close confined mater and with what type bearing/bushing on the shafts & how they stay/hold from the alu plate to shaft ?
Thanks for considering !
Robert
Reply With Quote
  #50  
Old Sat 29 March 2008, 08:19
zetacnc
Just call me: Fabio
 
Atibaia
Brazil
Hello Robert,

Well, the idea to build my own belt reduction was born when i tried to search already made reductions for stepper motors, or even motors with gear reduction like those from Vexta that are used by a lot of people here (in forum)...

As I told before, Brazil is not so good to find these kind of products, and importing taxes are very high...

I used as a starting point the original pieces (M5 10 312 and M5 10 322 motor swing plates) and imagined how to place one big aluminium 72 teeth XL belt gear as driven gear and a small steel 20 teeth XL belt gear as driver gear mounted on motor axis...
I also bougth a XL size belt (sorry don't remember correct length size), calculated the center distance between gears and started scatching some ideas.

The reduction is made basicalliy by two steel 10mm plates (but you can use aluminium) separated by 3 small collumns.

The final design is attached in DFX format - sorry if they are incomplet, but I asure you it's possible do build funtioning unit from them...

Each main axis, as I named the axis that the big 72 T gears is mounted is a 12mm diameter steel axis mounted on two 6001 ball bearigs.

Each bearing is press fit in a recess made in each plate as you can see in drawings, and there are two thin spacers between gear and plates (one each side) to maintain gear centered and not touching plates...

I then milled a flat recess in the shaft and installed a Allen screw to block the gear in the shaft.

The main shaft is protuding to one side to allow the module 1,5 pinion to be fixed with two allen screws (in milled recesses)...

In the plate where the motor is fixed, I milled a kind of recess to allow the motor slide in and out to adjust belt tension...

If you note in drawing, the width of the recess is smaller than the front of a NEMA 34 motor, and because this I milled two paralell flats in the motor front cover plate (without dismantling it! ) - (sorry I don't have photos).

The homemade reduction was them assembled over bench and then easily assembled in machine the same way the original one is mounted...

Attachment 1122
Attachment 1123
Attached Files
File Type: zip beltreduction.zip (14.9 KB, 646 views)
File Type: zip reductionphotos.zip (744.3 KB, 693 views)
Reply With Quote
  #51  
Old Sat 29 March 2008, 09:23
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
Send a message via Yahoo to Robert M Send a message via Skype™ to Robert M
FabioÖthe Fabiolous !!! < :0))

This is very well and superbly explained. It is very motivating & inspirering for me.
Iím no genius when it comes to metal working, Iím a meticulous custom & studio furniture maker.
Love Metal working, but do not practice nor do much, soÖ Iím not inclined to see those little things that may be obvious to others.
Thank for showing the way on this one to meÖ I owe you one
Robert
Reply With Quote
  #52  
Old Sat 29 March 2008, 15:41
zetacnc
Just call me: Fabio
 
Atibaia
Brazil
Robert,

Please, feel free to ask me any other detail that interest you.

I'll be glad to help someone else...

Best regards,

Fabio
O.T:
I don't know if you know this, but i'm very impressed with the detail:
http://br.youtube.com/watch?v=kvHYaR...eature=related
http://br.youtube.com/watch?v=GK5_Bl...eature=related
Reply With Quote
  #53  
Old Mon 05 May 2008, 19:36
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
Send a message via Skype™ to J.R. Hatcher
Marc and I have designed this 3 to 1 motor reduction. If time permits I will install one on the Z tomorrow and report how it does.
Attached Images
File Type: jpg MechMate1 017.JPG (22.7 KB, 3791 views)
File Type: jpg MechMate1 019.JPG (23.3 KB, 3768 views)
File Type: jpg MechMate1 023.JPG (23.5 KB, 3770 views)
File Type: jpg MechMate1 15.JPG (23.1 KB, 3761 views)
File Type: jpg MechMate1 013.JPG (22.5 KB, 3759 views)
File Type: jpg MechMate1 015.JPG (23.3 KB, 3769 views)
Reply With Quote
  #54  
Old Sun 18 May 2008, 01:34
jeep534
Just call me: archie
 
prichard, wv
United States of America
Jr,
Those reduction units look slicker than snot......
patiently waiting for more info. I would like to build one of the MM's to run a Plasma cutter. Keep Up the good work.

Happy Hunting
archie =) =) =)

(newbe to this forum but not cnc)
Reply With Quote
  #55  
Old Sun 18 May 2008, 06:02
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
Send a message via Skype™ to J.R. Hatcher
Jeep 534,for more information on the trannys look in my personal thread. Later when Gerald returns, he will possible transfer info here?
Reply With Quote
  #56  
Old Sun 27 July 2008, 08:34
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
Send a message via Yahoo to Robert M Send a message via Skype™ to Robert M
Some help needed on for my future belt / trany system !

Have a problem as far as where to post my question, here or with the power supply section, so Gerald please see to this & feel free the reroute my question ?!

Initially I got soooo intrigued by Mikeís posts on his polycarbonate belt reduction but then I got itch & influence with Fabioís version that it got me to the drawing board but finally got the kick and seduced by Marc & JR interpretation of their belt reduction trany system that I have no doubt anymore that I too will be making my own version but only after finishing & getting to run with success my version of the MechMate.

Question I would like someoneís help with is with the famous motor selection question.
Unbelievable the amount of time one like me who nose didly on motor / power supply section can spend on reading, sorting info & trying to learn to make the right final decision on those !!.

A note about my future set up is Iím designing my MM with an indexer. So, as far as this motor selection goes Iím still confused about the proper transformer/power supply.
should I consider getting all identical 5 motors to balance my future application or 4 identical for the MM and a different 5th for the indexer would not matter?
Would it cause some challenges when time comes to properly select the power supply ?

Example of what I came to select after some reading. No certain if those are ok but Iím aiming for 4 - PK299-F4.5 for the basic MM with 4:1 belt reduction and one PK2913-F4.0 for the indexer. I also intend to have belt reduction to the indexer motor set up in the range ofÖ.say +/- 15 to 25:1 via a double gear / belt set up ?

To some, maybe the possible torque obtained by this belt reduction with a PK299-F4.5 will be enough for the usage of the indexer, but on the other hand the extra torque available with the PK2913-F4.0 should be welcome if it as no penalty or negative effect in the electrical control box components selection & set up aside of itís extra +/- 100$ for it ??

Amicalement, Robert
Reply With Quote
  #57  
Old Sun 27 July 2008, 10:14
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Calculate the voltage of the power supply by taking:

32 times square root of milliHenry inductance

So for the PK299-F4.5 you get 50V and for the PK2913-F4.0 you get 65V. That means your power supply, if you use only one, must be 50V. That means your PK2913-F4.0 will produce less torque because it has a reduced voltage. About 23% less.
Reply With Quote
  #58  
Old Sun 27 July 2008, 19:03
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
Send a message via Yahoo to Robert M Send a message via Skype™ to Robert M
Thanks Gerald for your input.

Before going further Gerald, I thing this post should go to another thread. Please fell free to edit this one and the one before and redirect them !! ( or Maybe I should think starting my own personal page ?? )AnywayÖ..

Allow me to question on yours
But before, I should have been more specific about the how I intend to run the indexer motor at max torque possible since no speed is in need, therefore Iím assuming a Bipolar parallel motor mode is the right choice. If Iím perceiving this wrong, please redirect me, but bipolar parallel voltage needs to be set at 0.707 of the unipolar !
If I understand this math thing correctly, in the case of the PK2913-F4.0, inductance is 4.2mH unipolar or parallel, then the math goes:
S.root of 4.2 x 32 = 65V, but 65V x .707 = 46V
Due to my ignorance in this field, Iím not in a position to assume correctly, but couldnít I use this motor set up ( Pk299-F4.5 need 50V, & PK2913-F4.0 @ .707 needs 46V ) with a +/- 50 to 56V or even higher ?
Some are using the 56V with the Pk296A2A-SG motors, rated at 1.5mH and reported good results, questionable about their findings but still !!! ( S_root 1.5 x 32 = 39V ??? )
Where Iím getting even more puzzled about this voltage math, is when I read out of the Oriental Motor spec sheet their testing the PK299-F4.5 in parallel at 60V ??? See page C-229

where Iím with another dilemma is all this complexity worth my trouble for some extra torque, especially if I intend to have a +/- 30:1 to 36:1 multi-belt / gear set up ! ( I revised my gearing calculation vs the 15 to 25:1 as previously written )

Pk299-F4.5 Bipolar Parallel = 880oz-in x 30:1 = 26 400oz-in = 137.5 ft-lb of inertia capability
PK2913-F4.0 Bipolar Parallel = 1320oz-in x 30 = 39 600oz-in = 206.25 ft-lb
Thatís a 50% more inertia torque capability, but still only +/- 69lb !!!
Me to sort out, you to tell me Iím nuts or on track ??!!
Again, sorry to pull some of you guys hair, but havenít you all gone through or close to this in the past !!

Thanks you very much, Robert
Reply With Quote
  #59  
Old Mon 25 August 2008, 03:36
D. van Randen
Just call me: Dickie
 
Sydney
Australia
MULTI national belt reduction

Sometimes its nice to see how the big companies put there product together.

Investing millions in making and maintaining their reputation in the CNC market they pin it on belt drives, a rugged, simple way of gear reduction that looks to have the ability to have backlash adjusted out when ever needed.

I have seen this method used on their smaller budget machines and also on their higher end models with complete tool changing systems.

The gear reduction is 3.75:1 . Sorry I did not count the pitch on the drive pinion or the rack.

D
Attached Images
File Type: jpg Multi Gear.jpg (43.0 KB, 3444 views)
File Type: jpg idler_adjuster1.jpg (42.7 KB, 3439 views)
File Type: jpg adjuster2.jpg (45.7 KB, 3431 views)
File Type: jpg rack.jpg (50.0 KB, 3445 views)
Reply With Quote
  #60  
Old Mon 25 August 2008, 05:41
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Interesting parallelogram they have there - seems like the pinion is already on the small side and the motor is in danger of fouling the housing at the top. Thanks for the pics
Reply With Quote
Reply

Register Options Profile Last 1 | 3 | 7 Days Search Today's Posts Mark Forums Read

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Belt reduction box build T5 16 to 60 linus1 Driving Mechanisms: Rack/pinion, gears, screws, belts & chains 3 Sun 25 July 2010 09:26
Belt reduction installed, cutting metals - Big Lake, MN chopper MechMates already cutting 61 Tue 24 November 2009 00:02
Has dust foot, belt reduction and plastic wheels #22 - Midrand, S. Africa MariusL MechMates already cutting 124 Fri 23 October 2009 04:33
Trying smaller motors with belt reduction #17 - Sao Caetano do Sul, SP, Brasil YRD MechMates already cutting 178 Sat 04 July 2009 09:59
Off the shelf belt drive? myozman Motors & their mountings 2 Mon 22 June 2009 20:41


All times are GMT -6. The time now is 15:12.


Powered by vBulletin® Version 3.8.3
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.