If module 1 rack then what I found is only 20, 26 and 30 tooth pinions , the lower number of teeth slows you down but increases resolution,
What I seen almost everyone use 30 tooth module 1 (3.14 or PI, tooth distance) with belt reduction 3:1

you can use 12 or 24VDC depending on the relays, contactors and other stuff you plan to use on the machine

Thanks Danilom !

Yes Module 1. Then I order 20 and 26th or 20 and 30 tooth- so I have two options in the end to experiment if necessary.

I am willing to sacrifice speed for increased resolution but only if necessary
I am doing the 4:1 ( I know about the theoretical wrap issue - ) though.
I thought I read somewhere here that 20 tooth works only with inch based racks, and that 20 tooth on module 1 would be too small to use grub screws ?
( But I read so much the past week, and slept so little that I sometime think I hallucinate)

Ok, I will decide the second output to be 12 or 24 based on the rest of my system, so besides that my calculations/assumptions are correct ? (I need to start ordering..)

48V should be ok for motors supply

if a pinion has a too small collar for grub screw, same as 15 tooth pulley which I had to bore to suit 14mm motor shaft,
what I do is drill two-three holes (depends on space availabe) and tap a thread to connect it to a larger piece (if possible I welded it couple of times). I think it could be the term "hub" to call that piece which is added to the pinion or pulley.

You need to make sure your voltage matches your motors faily close so that 48 should be fine. You may want to explore other motors as a cost savings if they are available. The price point in the States for that motor is almost 3x a comperable equivalent. Also I have seen in a lot of the newer builds not having secondary output DC voltages in the box. This keeps the costs down on the PS. Unless you have specific designs in your cabinet for the lower voltages, they are really not needed with the newer BOB's. You just need to make sure your BOB can run off of 110 volts like the PMDX-126 can. If I am remembering correctly the older setups used the secondary DC voltages to power the older PMDX-122 BOB's.

Thanks Mike,

I'll keep that in mind. I was looking into Motion King and Leadshine for savings (saw this savings story pop up somewhere else). But... I am very limited in time, so I might just cave in and stay with the current choice, my head is hurting and time is running out quickly. Just finished calculating all my cutting list and lasercutting for the steel, mailed it out to 3 vendors, hope to have answer today/tomorrow, going to bed now (3PM )...


Danilom; found this on the pinions again: is this old or still active in terms of suggestion for my pinions in metric with 4:1 drive ?

http://www.mechmate.com/forums/showt...5&postcount=39

24 tooth is the minimum for "module 1" gears . Correct.

(if you use module 1.5, which has bigger teeth, you might be able to go to 20 tooth, but I have not studied it. Module 1.5 is not so common as module 1. The best smoothness will be with module 1)

And...awake again (since 1,5 hours).
Luckily I am "combat trained" by my 2 years old :)...but that was a short night again.

Thnx Gerald !
I will order the 24 tooth and the 36tooth option then. I need smooth, so Module 1 will be it.

I've spoken with my friend ( in the steel trade) about your plans, and he was impressed with the thorough and clean job you did on the plans. So am I, now I am diving into all the little details. Even though I was already up to speed with the general plan, I must admit it's quite a time-consuming (with my deadline) read to find/figure out all the details needed on a build ( I know why you choose this strategy ). But the good thing is almost always when I start looking I discover that somewhere on this forum you typed the answer.

@ Mike can I also buy a .dxf for the proxy switches time saver of you ? Would be more convenient/economic for me if I can order them with the lasercutting parts.

I can ship a set to you in the post. I can send you an invoice

or

Look here

http://www.mechmate.com/forums/showt...4&postcount=23

Ah, thanks added them immediately to the lasercut files !
Normally I would buy them from you but with this deadline it's quicker to cut them with spiders etc !

Can anybody confirm what my total width would be of the table with effective cutting surface of 3100x2100 mm ? Maybe measure your own table ? I know I would need to add 500 mm to the Y, but I think the motors are sticking out over that ?

I need to know how much room I will have left in my preferred designated area which is a bit tight (8000 x 3450 mm wall to wall ) to be able to walk around ( on one side ?) the machine when it's operating.

fox,
For my machine add 36cm to your y axis (measured over the outerside from the C profiles. my motor+ gearbox is 14.5 cm outside the c profile
total to your y is 36 + (2x14.5) =65 cm

Thank you Ric,

don't know where I would be without you guys !

The absolute total width is from the back of one of the X axis stepper motors to the back of the other, so it varies a small amount depending on the size of the stepper. Normally, the front of the stepper is 20 mm or so beyond the length of the gantry steel. Belt drives push things out another 30 mm. So, a working estimate is that you'll have 2100 + 500 + 2 * ( 20 + 30 + 100 ) = 2900 mm in your 3450 mm space.

Presumably you'll do full sheet loads into the end of the table, and perhaps place one long side against a wall. That would leave you with a small area in the middle at the back that you would not be able to reach without climbing on the table. My space is constrained on two sides, and I have to load over the rail and climb to get anything at the back rail; I tend to layout my sheets so that I don't have small pieces at the back side.

You won't need 850 watts worth of power - all four motors will never draw their maximum at the same time. There are plenty of successful reports at 300 watts; there is no risk in going over, it just costs money you don't need to spend. Since most folks aren't comfortable when they hear this, go ahead and get a larger supply, but you might consider something in the 450 watt range instead.

You may also want to consider using "half coil" wiring instead of bipolar parallel. You can read up on the pros and cons elsewhere on the forum. This needn't affect your ordering,

Hi Brad,

valuable insights. Stupid but I did not think about the engines not all being loaded at the full at the same time, but hey... it's my first CNC.
I will downscale the power supply, saving money is good.

Space is a bit tight indeed, my workshop size is comfortable, but divided into many different rooms ( not just drywall- they use real stone here in the Netherlands :) ) So this room the best/quickest to clean out place I have available right now ( now storage/junk room) My workshop itself is bigger, but don't want to take up all the floorspace there with this big machine obstructing other work/machines.

Your tips on parts planning will be taken into consideration. I was also contemplating if after cutting your could just pull the cut sheet towards you to slide the cut pieces with it, being able to pick them out one by one ( drop them on a cloth on the floor ), a bit like a conveyer belt. ( with 20 mm mdf this become heavy work - but with a sheet of 4 mm plastic it might work, if the spoilboard has not yet seen too many cuts ? we'll see.

Hi Gerald & others;

Asking for a second opinion:

For a MechMate with bolt together table frame with flanges like seen on the forum for instance by BuiBui.

Option A) the left side
Option B) the right side

http://s13.postimage.org/jrf5wz8pf/mechmate.jpg
I am using an Wide flange 200 x 100 mm I profile for the main beam.
I am using 50x50x5 mm beams for the frame.

Option A allows me for regaining some more of the lost space under the table for storage of boxes etc.
Option B is true to the original design, but using square box profile instead of tubes.
I would choose Option A, but only if I am not comprising the performance/strength of the frame in a significant way. Then I would fall back to option B) and triangular boxes :-)

Option B is more rigid.
Option A is still more than adequate.

All those options limit direct access to the underside of the table as you have to lift objects over the lower bar.
Please note that storage of items / sheets would normally be slid in from the short side or what some might call the ends of the table.
The table is also typically loaded from the ends, so having your storage strategy consistent with that is quite important.

A better option is to diagonally brace the long side of the table as per the plans.
For the table ends if you wish to use the underside as sheet storage see the pic.
Attachment 13687

There is a strong focus on the table design in the forum with lots of variations on the basic theme.
Typically these variations are mostly cosmetic / vanity modifications as is quite typical of the average DIY fan.
The real issue is reading the plans in fine detail and understanding how the table goes together.
The business end is the upper table, the electronics and the software control and tuning.
Set your goals for your storage requirements and quickly move on to the main game if you are on a short time frame for the build.

If you intend to bolt the table as myself and Bui Bui have done, expect this to take more time to build.
To make this process as quick as possible you should draw your own CAD lower table drawings to highlight any clashes with the bolt connections.
The CAD drawings will also give you the ability to make mild steel drilling templates out of flat bar for your hole spacing's.

Not all measurements are directly provided in the plans and they will need to be inferred from your chosen table size.
Until you can calculate these measurements on your own, you can assume you do not know the plans well enough to proceed and get it right first time with no redo's.

Regards
Ross

Hi Ross,

Thanks for all the suggestions.

I already did the drawing I show myself in CAD, luckily I am fairly quick with CAD.
Even though the deadline I wanted so spend one day and night on checking the thing in CAD, for issues. Found some and corrected. Also understand the dimensioning much better now. Was just wondering about the compromise in strength between these two designs for the side, I am not an engineer, and have not run a CNC before. I do understand we want the main beam as stiff as possible, and a diagonal is generally stronger, as they triangulate the hell out of cranes and such I was just wondering if this solution would be "good enough". I figured I loose some strength, and maybe gain a bit by using the I beam for the main beam so I would be ok, but I just am not sure about that. if there would be thousand KG on the middle of the BIG beam, i would for sure take the diagonal route, but with the router most forces are sideways, wanting to rack the thing, which I hope to catch with the ladder construction ?

I do have left a little space to slide some stock 2050x3050plates in from the front, but I designed it so it is only small, as I think adding a lot of boards will quickly add many KG in weight, which will start pulling on the structure and that can't be good. Other stock will be slid, under the machines lower beam, or elsewhere.
I also asked BuiBui about this design and he has replied me he has not found any movement issues other then he would replace the top beams with the C profile like in the plans ( he used box ). So I guess I should be fine. If it really tuns out an issue I can always add an diagonal later in the left and right square of the ladders.

Ps. I have to send out the cutting list tonight, so I just need a second opinion before I make a stupid mistake in search of some storage space :)

"Standard"
http://s2.postimage.org/reny7vxyd/me...andard_big.jpg

"Adapted design"
http://s7.postimage.org/cw6q8zjbr/me...design_big.jpg

you can start building and order the laser parts while you asemble the base table.
remember you have to asemble the table and paint it. once you have the base table you can cut the rails on it at least one day cutting.
if you are alone there are some things you will need help like moving the gantry..

Hi Fox,
1 month is "enuf" (not plenty) time for this build. The main trick is to have all the necessary parts & material in hand & a pair of helping hands for heavy lifting & assemble the table.

Of all the works, the rail grinding is the sucker, not difficult, just time consuming. I would strongly advice you start grinding the rails once you have the skate in hand. AND DO IT OUT DOORS!

DO NOT skip the Kitchen table project before any electrical installations, you had been warned!.

A bolt on table will take at least double the time to build then a weld-on, because you will need to prepare the brackets (unless you have a pair of helping hands) & most importantly it is harder to align everything together (even if you have a pair of helping hands). I know because I'd built both.

Prime your steel before you do any cutting will save plenty time at the end of the build.

You only need 300VA transformers for the PSU, just take our word for it if you have no time to read through the forum. & yes, 48Vac is a good choice. Don't forget that you need at least 20,000uF capacitor with at least48V rating, 65V is my choice.

If you need DC for your bob or other light load electronics, just grab a wal-mart wall plug or any cellphone charger for the job. will save you plenty of time & money..

For direct drive, 24 teeth is the smallest pinion physically possible to fit on to your stepper motor shaft.

Take down a wall if you can, collecting the cut parts is PITA when you can not access from the side especially when they are small & plentiful.

Take time to level the rails & do better than your best to ensure every part of the table is square & through.

STEEL IS ORDERED

@ Fernando
painting afterwards, not now. Table building will be finished next week with help of my friend in the steel company.
@ Ken.
Rails are indeed an issue. Asked for quotes on V rails to cut time short. If in US I would have ordered from Superior bearings. Quotes in NL for V rails + wheels are crazy, unhardened rails for my machine about 2000 euros (!)... I can buy Hiwin linear guides for that ! If time schedule permits it will be the DYI grinding, will perform test with skate in hand next week to calculate time, already ordered enough L profiles just in case.

I am on a 4:1 gearbox with belts, but on geralds advise will use 24 tooth for gear.

I will square everything with micrometer. Table is built in professional workshop with all tools/weldingtables/clamps available, I hope we can get it into 1 mm accuracy on frame. I hope I beams for main will help reduce warp on the mainbeams.

Bolt on is necessary for transport movement in and out of my shop. I know welding is quicker and stronger, but it is like it is... So bolted it will be.

First assignment has to be in small room, later we will see.
I can walk around it see image.

http://s7.postimage.org/ouof4io4n/mechmate_in_shop.jpg

I know a H500 x W400 x D150 is minimum requirement for a control box.
I want to mount my box in between my side frame, where I have a space of W825xH400 mm.
Looking for boxes I can place a W600 x H400x D210 box in there so doors open standard. So basically a bit bigger then the minimum "portait" version, but then laying in "landscape" modus.

I wonder: could I manage fitting my electronics horizontal in this box ? Or should I stick with standard postion ( remember my box is laying down, so standard horizontal rows will become vertical in my box ! )

red box is electronics box, green one will be VFD box.

http://s1.postimage.org/fiun1w7hn/mechmate_control.jpg

You can also mount the electronics on the wall above the machine. If you do re-orient a box, think carefully about the hinges.

I want to make a quick comment on the prefabricated V-rails.

They do not save you time.

To properly mount the V-rails you have to cut the support material - aluminum architectural angle - to height. Then drill A LOT of holes - precise holes.

After assisting Nils during his build and watching the effort, it was clear that the amount of labor hours was equal, if not longer with the prefabricated V-rail.

Just my view from doing both processes. Don't interpret this as a negative for the prefabricated rails - I love them.

But from a purely time sensitive view, it's not a time saver. With the proper set up on the skate with an agressive 36 grit disk to do the major profiling, I bet I could do all of the rail fabrication in 2 days flat by myself.

Fox,
orientation for your electrical components should not be an issue. if i see the picture of your available space I should also consider wall mounting. Do you see yourself laying on the floor clamped between the mechmate and the wall doing some trouble shouting? if mounting under the machine, check if you can open the door. place the machine that you can just walk between, and chose which side you mount the cable gutter ( I decided my one wall side)
Working outside at this moment is not an option If I hear how the weather is in holland. I received snow pictures today

@ Brad; I can't really do that: in my room it will: obstruct my walking, or has to be mounted too far away, or above the table. Hence this location ( good tip on the hinges, I already looked into the spec for some data on this, could not find it. Will now order big box first so I change size on vfd box if needed because of the hinges, leadtime is short luckily.

@ SM;
noted. I might use linear rails, but go for grinding first.

by pure luck I got offered lightly used second hand linear SKF rails the other day while talking to someone. And 2x3,5 meters of 25 mm linear rail for a few hundred euro total ! I thought SCORE, could not believe my luck.
But then found out:
the two rails are no longer produced by SKF, and they have only two carts with them. No newer carts will fit acccording to SKF, their advise was... buy new ones ( @4000 euro). Then I thought... hey... I buy one new rail of the same dimensions, it will still be a good deal. And then I calculated the X amount to buy the new rail and it is 3850 mm.... so that stings a bit ( I thought it would be around 3,50 meters or a bit less with my X of 3050, dunno why I had that number).

Still contemplating on buying them just for the Y, but a bit hesitant, because of matching two different brand rails then ( friction?!)+ if I have to machine v rails anyway for the X the Y is relatively easy work.

@ Ric
Great ! Strip that off the list. Ordering all electronics etc. this weekend. Wall mounting is not really viable...see above.
I was contemplating on mounting the box after all initial troubleshooting is done, just have it losse in the room on some trestles. I hope I do not have to lay under the table under daily basis once its up and running ??. And then maybe still mount with quick releases, and have some "loose" cabling so I could again put it on a stool, for more convenience if/when needed. I see a lot of commercial CNC have the boozes on the table, so I guess it'll work somewhat.

Dutch: Sneeuwt en vriest idd lekker, dat zal wel tegenvallen straks bij terugkeer:). De elfstedentocht waanzin "het-gaat-echt-wel/niet-gebeuren-dit-jaar" is al weer losgebarsten ;)

Can any body point me towards the best compatible stepper from www.motionking.com
as an alternative for my current choice oriental PK299-F4.5A ?


I am a bit lost, so may specs so many options, don't want to make the wrong decision.

http://www.motionking.com/Products/H..._1.8degree.htm

Would this be a good option: 34H2B9850 ? (I see they only make Bipolar on request)

Those are like I use, my friend Milan and Pajka from Macedonia, they are Deitech 86HS9802 same spec. 5Amps and around 45V is ok for them, others used 9801 on Mechmate its a lower Amps but higher voltage motor but with same torque. Depends on your drives.
If you use DM856 from Leadshine or Gecko then you can use the 9801 one.

I don't know if I understand the last sentence correctly.
I see your friend uses DM856 from Leadshine to drive his Deitech 86HS9802 motors.
This turned out to be a wrong choice andhas been replaced ?
Or do you mean if you use this driver or the Gecko 203V you can choose between the 9801 or 9802 bases on personal preference ?

I do notice it saves a considerable amopunt of money to go with the leadshine vs gecko and motionking vs Oriental, so I might take that route and spend it on some otehr parts like linear drive.
But then if I understand correctly you did not wire them Bipolar parallel ? Or did you order that custom, in short: how did you hook them up ?

I believe he was referring to the fact that some drives are capable
of using higher rail voltages than others. Some motors cannot be used with some drives,
as the require a rail voltage higher than some driver can support. The gecko 540 is limited
to 50V rails for the motors, so you have to pick motors that work with up to 50V and no higher for example.

Thats right Heath, I meant that with 80V capable drive you have more motor choices.

DM856 is THE most silent and smoother drive I have seen, we accomplished feedrates of 42000 mm/min

Wire bipolar parallel and have no worries. It works best for me.

Cool.. I save almost a 500 euro on that combo; no-brainer, ordering from Deitech !

Ok, working things out with Deitech at the moment, want within teh next two days... for engines, controllers, e-chain etc.

QUESTION: Should I also order some milling bits from them while I am at it ? Or should better stay away from 'Chinese' cutters ? My experiences with drill bits on this topic.

If so; anybody got some tips on what an absolute beginner should order for starters ( some basic cutting mdf, doing the spoilboard leveling, some bits for testing alu, and cutting polycarbonate acrylates ? ) THNX !

For basic cutting with carbide spiral up-cut bits look for carbidechiu on ebay, I use bits from him all the time more than a year. Even some dia 10mm hrc55 labeled I use for hardwood cutting, guitars and stuff, it cuts like hot knife trough butter and stays sharp for ages.

For spoil board there are large diameter bits for leveling.

For aluminium look for single flute bits but not all work nice, it depends on the geometry of the tool.
Same thing for polycarbonate or acrylic plexiglass cutting, single flute 4-6mm carbide.

Best thing is to find one from a well known manufacturer and try it, if it works ok but the price is a bit high look for a Chinese equivalent, for important jobs use real quality and Chinese for every day cutting.

In the end everything depends from proper feeds and rpm.

Again asking for urgent help:

86HS9801 engine
Leadshine DM856

engine spec: mH 4.1, 4A
I want to wire it Bipolar parallel.
I do not see different specs on the Deitech site, but it does state 8 wires.
Do I need to multiply the amp value ?

If not

32 x √4.1 = 64,79 Volt
5x4=20x0.67=13,4x64,79=868.18 VA/Watt
( taking one extra engine into account for future 4th axis here).

Watt can be around 300-500, and still be fine everybody says ( engines not asking full power all at once ).

Then I wanted to built my own powersupply, cause Antek will be to much delay, and no local alternative:
DYI powersupply

toroid, check: use a 64 volts, 400 va

rectifier:Ehm...64 volts x 1,41= 90,24 volts ?!? Will that mean I kill my drivers (also 80 volt max) the instant I put power on it ? What am I missing here ? Should you have taken this multiplying factor into account when talking the DIY route; choosing the toroid lower then the calculation suggests ? - not mentioned anywhere- I am lost in this electrical mambo-jumbo.. and time is running out quickly. Please help !!

I continue the math for the capacitor just in case...
Capacitor=mF=(8000*I)/V= (80000*20)/64=25000mH= 24000uF (only one available), 100V ( this also needs to be able to take the 1.41 higher voltage, I've read ) or I could/should I just hook up 3 x 10000 uF x 100 volts ?

no you divide by 1.41 , that is the voltage output of the transformer, after the capacitors do their work it will be 64V

you can parallel 3x10.000uF

bipolar parallel current for 9801 is 4Amps , 8 wires gives you 4 separate winding which you can parallel to get bipolar PARALLEL connection.

This and other information given here are very valuable and should not be taken for granted, what you need if you get into building this machine is to understand all this and its done with reading build logs and discussions about these information to get a better insight into it.

Regards

Danilom, believe me I have read/still am reading a lot on this forum. Metalhead can probably see that by my user statistics over the past few weeks. And I've read a lot over the past years ( I am member since 2008) I am not being lazy. I thought I understood it, but electronics are not my strong point. The information is often so splintered, often a thread starts out with a conclusion which at the end has 10 other conclusions/suggestions. I am not moaning about that, just asking for help and explaining why, casue I want to understand every bit on this machine.

I thank you VERY much for your quick reply, but I am very sorry to say I do not completely understand the answer:

What do I divide by 1.41 ? Are you saying that I should have divided the outcome of the voltage calculation for the toroid in this post as I suggest above ? Do I completely missed reading that in that thread or is it elsewhere ?

If you need 64 Volts to power a stepper drive, then a pure transformer output should be 45V AC !

After bridge rectifier and capacitors you get 64V DC

Your 64 volts you calculated is DCV. Therefore you divide the 64 by 1.414 to get the ACV of the transformer you need. In this case it would be a 45V AC transformer secondary. When rectified and filtered it would give you the 64 VDC you calculated. :)

Sorry Danilo, guess we were typing at the same time. :)

THANK YOU ! for putting up with me-helping me out. Appreciated.

Ps. So, my hunch/back reasoning after reading this figure in the rectifier thread and getting all puzzled was correct, and I do understand this stuff a tiny little bit, or at least now I do.

But.... how ever did you guys figure that out when you were first building and knowing nothing ?! Same way ? Or am I really the first one ever to be so stupid ?

Imo it woudl be a good idea to put a small tip "for DYI powersupply toroids divide this number by 1.41" on this in post 1 here: Calculate the Voltage and VA size of the DC power supply for stepper motors/geckos.

Or at least fix the link in that post; part of my confusion was fueled by the fact that the link Or consider to design & build your own. in post 1 links to the same thread/calculation, instead of this as i think it should ?

No offence, conversion from AC to DC is really a very elementary, I'm very sure its been mentioned many times. If you had googled, you will find enough information to fill a library.
I remembered I have a few very comprehensive calculation in one of my building threads.
The forum is a treasure of info on CNC building. but sometimes, you gotta look else where suit your learning level.