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  #301  
Old Thu 11 March 2010, 21:48
swatkins
Just call me: Steve
 
Houston
United States of America
Here is a post I wrote a few days ago explaining how I tap and some things to make your life easier.. http://www.mechmate.com/forums/showt...3&postcount=49



Here is a picture of the setup I use on my lathe... Drilling the hole takes 10 times longer than runing the tap in! Sorry for the picture quality, All I had was my phone...

tap.jpg

I chuck up the standoff, cut it to length and then drill the center hole... Then I place a spiral point tap in the drill chuck mounted in my tail piece.. I LIGHTLY tighten that chuck! IF the tap force is too great the tap will spin instead of breaking.. I do not tighten the tail piece so that it will slide along the ways easily...

I then turn on the lathe in forward direction and push the tail piece into the work with my hand... The tap takes a bite and starts threading into the stand-off. I have my hand on the reverse and when the tap is almost complete I reverse the machine and back the tap out...


I wear a face shield for safety. You must have a spiral point tap, really lube up the tap well, go slow and be ready to stop or reverse in an instant... IF you have the tap in the drill chuck correctly the tap will work but also spin if you get into trouble...


Steve

PS Why to these pictures allways make my lathe look like it is a rusting piece of junk?

Last edited by swatkins; Thu 11 March 2010 at 21:55..
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  #302  
Old Fri 12 March 2010, 06:32
jhiggins7
Just call me: John #26
 
Hebron, Ohio
United States of America
Thanks for the instruction, Steve. I always enjoy your tips and techniques information. Thanks for taking the time to share it.

Your "junk" lathe looks beautiful to me...especially since I don't have one but would love to.
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  #303  
Old Fri 12 March 2010, 22:45
cordell
Just call me: cordell
 
johnson city,tn
United States of America
here is what I used for stand offs, cheap, already threaded, come in different sizes, pick em up at most hardware stores, chuck them up in lathe and cut to length. http://www.drillspot.com/products/49...upling_Nut?s=1
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  #304  
Old Tue 20 April 2010, 15:54
Regnar
Just call me: Russell #69
 
Mobile, Alabama
United States of America
Pivot Point

I was just wondering if the pivot point is on the same side in all locations. I ask because I am about to countersink all the plates for making Leo's Belt Drive setup and you can make it go either way, but after choosing which way you will have a hard time reversing it.
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  #305  
Old Tue 20 April 2010, 22:49
swatkins
Just call me: Steve
 
Houston
United States of America
Did you get your parts from Leo?

Mine were from him and he used a different setup on the gantry plates so that all the belt drives could be made the same...
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  #306  
Old Wed 21 April 2010, 17:54
Regnar
Just call me: Russell #69
 
Mobile, Alabama
United States of America
Thanks Steve, I had thought all of them where built up the same but looking at other builds I had started to notice different directions. Finished countersinking all the plates today and will prep, prime, paint and press in the bearings. I did a mock up of one and all I can say is wow. They are nice!
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  #307  
Old Wed 21 April 2010, 19:04
swatkins
Just call me: Steve
 
Houston
United States of America
Quote:
Originally Posted by Regnar View Post
Thanks Steve, I had thought all of them where built up the same but looking at other builds I had started to notice different directions. Finished countersinking all the plates today and will prep, prime, paint and press in the bearings. I did a mock up of one and all I can say is wow. They are nice!

I posted a few pictures of the ones I built on my build log... http://www.mechmate.com/forums/showt...4&postcount=67

There is also a picture of one mounted to the Z axis. I had to make a spacer to get enough clearance.

Another thing you want to watch out for is the heads of the screws that mount the motor to the plate. Find screws with a very thin head... I like stainless cap screws and bought them for this application but the heads were problematic.. The heads interfere with the large tooth gear and the pivot mountings...
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  #308  
Old Wed 21 April 2010, 19:23
Regnar
Just call me: Russell #69
 
Mobile, Alabama
United States of America
Thanks again, I must have looked at your thread 30 times now and just noticed the geared motor

I see you are using button caps under the gears that mount the motor. Is this what you mean by the clearance and are they working out for you. The button heads are what I had in mind seeing I have a huge abundance of them.
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  #309  
Old Wed 21 April 2010, 19:45
swatkins
Just call me: Steve
 
Houston
United States of America
Yes they are the ones I ended up using... The clearance of the tooth gears is very close and the heads must be thin to miss the belt and gear...
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  #310  
Old Tue 04 May 2010, 12:17
Todd Bates
Just call me: Todd
 
Portland
United States of America
Quote:
Originally Posted by Richards View Post
Edgar,

It looks like the 3:1 belt drive that you referenced is for use with 23-frame sized motors. I would not recommend that size motor. They're just too small for the job.
cncrouterparts.com now has a drive sized for nema 34 motors.
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  #311  
Old Wed 05 May 2010, 04:51
Besser
Just call me: Besser
 
Vic
Australia
Hey guys, chrisd7306 is your friend, he's just finished a design of a gearbox. It's really in the MM design as it uses the current mountings, allows for balanced weight around the pivot and is easy to assemble. While I had some limited input in the design, Chris tried to avoid fabrication processes and if you integrate the profiles into your laser cut list at the start, the job becomes a cinch. Nema 34 XL belt drive with plenty of wrap. Keep am eye out for the shim plate and reversed flange nut (only cos they were my ideas....

So keep an eye out.
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  #312  
Old Tue 25 May 2010, 19:28
swatkins
Just call me: Steve
 
Houston
United States of America
I am trying to set up Leo's belt drives in Mach3.. Would anyone, who uses his drives, have the "Steps Per" setting for Mach3?

My heads hurts tonight and I think I would mess up the calculations
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  #313  
Old Tue 25 May 2010, 21:27
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Figuring things out is easier than you might think. We'll assume that we're using a 30-tooth spur gear that has a pitch diameter of 1.5 inches. We'll assume that we're using a Geckodrive stepper driver that requires 2,000 steps per stepper motor shaft rotation. We'll assume that we're using a belt-drive that has 4:1 reduction, i.e. 18-tooth to 72-tooth.


1.) Find the circumference of the spur gear: Multiply the pitch diameter of the spur gear by PI
1.5 inch X 3.1416 = 4.7124

2.) Find the distance traveled per step: Divide step 1 by the number of steps per stepper motor shaft rotation, which is 2,000 for a Geckodrive
4.7124 / 2000 steps = 0.0023562

3.) Factor in the gear ratio: Divide step 2 by the gear ratio
0.0023562 / 4 = 0.00058905 inches actual travel per step

4.) Compute the steps per inch: Divide 1.0 by step 3 (find the reciprical)
1 / 0.00058905 = 1697.6475 steps per inch

Just change the numbers to match the parts that you use and you'll have a close estimate of the required steps per inch. Be sure that you run some tests to check things out. It's impossible to economically make perfect spur gears, racks, pulleys and belts, so write some code to move an axis 10-inches and then measure the actual distance moved. Divide 10-inches by the actual distance moved, and then multiply step 4 by that number. If necessary, repeat the test several times until the discrepancy is too small to measure. Example:

10 inches commanded / 10.5 inches actual = 0.952380952

1697.6475 X 0.952380952 = 1616.8071 steps per inch
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  #314  
Old Wed 26 May 2010, 04:23
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
There is a button in mach3 that does this automagically, its on the settings screen, bottom left, called axis calibration.
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  #315  
Old Wed 26 May 2010, 09:32
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Look at Mach3 Tutorial videos here, then go to troubleshooting and there, fast-forward up to +/- 5 minutes, you’ll find the full explanation on how to.

Second, we have around here a excel spread sheet that can help you do those math manually, but again, why use the simple way when one can go the complex way…..

Mach tutorial will show you how to do this almost automatically, but for those like me who like to go the complex way, here Gerald excel table !

Amicalement, Robert
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  #316  
Old Wed 26 May 2010, 11:56
Kobus_Joubert
Just call me: Kobus #6
 
Riversdale Western Cape
South Africa
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I used the calculation to get it CLOSE, then use MACH3 axis calibration to fine tune it. Ran the calibration over a long length and this gave me a good result.
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  #317  
Old Sun 15 August 2010, 03:45
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
Belt Reduction Build Process

After having seen some questions on the forum regarding how to build belt reduction drives, I have decided to document the process I followed. I originally wanted to make mine with aluminium but after having some difficulty with cutters and cutting the aluminium decided to make the first units with Tufnol (Fibre and phenolic composite mainly used for electrical insulation but has good mechanical properties and machines well and easily)

SU Design side 1.jpg SU Design side 2.jpg
Step 1: Finalise design (This one based on JR’s original). I am using a 4:1 reduction so needed a bigger area for the driven pulley.

XY drives dwg.jpg Z drives dwg.jpg
Step 2: Arrange parts in material to facilitate machining – I am using dowels machined through the material and into the table for registration to enable machining on both sides. (The six holes around the perimeter of the plate) I have also used dowels inserted into the table to enable me to register the plate for the first operations (drilling). The square on the left in the drawing is to give me the required offset from the origin (100 x 100mm). Due to the differences between the XY and Z mounting plates I have made slightly different respective layouts. The above drawings show the machining that will be done on both sides of the plates. For the first plate both sides are the same giving one two complete sets, but for the second plate you need to keep your wits about you as one needs to run the XY file for one side (top area), flip the plate then run the Z file for the second side (top area) then the XY file for the bottom area to cut them out and flip the plate again and run the Z file for the bottom area to cut them out. This seems complicated to explain but will hopefully become clear below.

01 blank plate.jpg
Step 3: Clamp the plate to the table against the registration dowels. The screw down clamps I am using are made from Maple and have different height steps machined on each end to facilitate clamping different thickness plates.

02 registration dowels.jpg
Step 4: Drill the registration holes through the material and into the table – when done insert dowels through into the table

03 first side rebates.jpg
Step 5: Machine the rebated areas and mounting holes for the first pair of sides. Note the rebated area for the small piece is bigger than required to make sure that the entire surface is clean once cut out from the other side.

04 flipped over second side rebates.jpg
Step 6: Unclamp and flip the blank over using the through dowels to reposition it to machine the other side. Screw the blank to the table using the mounting holes drilled in the previous step. (note I have removed the dowels in the table along the X axis as the plate was slightly oversize and is actually partly covering those dowel holes – that’s why I am using registration dowels through the plate to make sure the positioning is accurate) Then run the same file again to machine rebates for the second pair. (When doing this step on the next plate be sure to run the file for the Z reduction at this point).

05 bearing rebates 1st unit.jpg
Step 7: Machine the bearing rebates, through holes and captive nut slots for the motor in the first pair.

06 Cut free from blank.jpg
Step 8: Cut out the first pair of sides. Flip the blank again and repeat from step 7 for the second pair of sides. (Remember to change files if cutting the Z pair)

Done! – two sets of sides to make belt reduction drives, now just rinse and repeat for the other two.

07 finished cut components.jpg
The complete sets of parts cut on the MechMate, the slightly different Z axis drive is on the right.

As an aside I noticed a small anomaly when machining my sets. The bearing rebates on the small pieces were slightly bigger than the bearing rebates of the bigger piece. The bearings go in nice and firmly with moderate pressure in the big pieces but virtually fall into the small pieces. I rechecked the drawings and both are exactly the same size. The only reason I can think of is the resolution of the direct drive system and the relative position of the respective holes on the table. Once I have the reduction drives assembled and fitted I will run these same files again and check the results.

Here is the PDF of the above process:
Belt Reduction Build Process.pdf
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  #318  
Old Sun 15 August 2010, 07:41
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
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Alan, very nice ......... design and presentation. I like the material, I bet it holds up just as good as alu and is much easier to machine.

Last edited by J.R. Hatcher; Sun 15 August 2010 at 07:44..
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  #319  
Old Sun 15 August 2010, 08:12
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Great work! Alan, is there any chance that the bearing rebates in the smaller pieces were cut in a conventional direction and those in the larger were cut in a climb direction?
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  #320  
Old Sun 15 August 2010, 08:52
KenC
Just call me: Ken
 
Klang
Malaysia
Fantastic work! Always wonder if those Tufnol are good for structural use.
Maybe lighter cut will help with the hole dimension.
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  #321  
Old Tue 17 August 2010, 12:08
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Great work, like this alternative material !
Once I have the reduction drives assembled and fitted I will run these same files again and check the results.
This will be v-interesting to read !
Later, Robert
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  #322  
Old Tue 17 August 2010, 18:40
Rad Racer
Just call me: Wayne #25
 
Minnesota
United States of America
Nice design Alan, I like it.

Be sure to watch your motor tempertures during extended cutting periods....Tufnol won't sink heat like aluminum. I ran into this issue with the gear drives I made from Delrin (plastic).
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  #323  
Old Wed 18 August 2010, 04:58
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
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Thanks for all the comments.

I have checked the files again and both holes are cut to the same specs with the same direction and with the same cutter the only difference is the position on the table. I am sure a lighter cut or rough passes to close on final depth with a finishing pass only taking off 0.5mm will give better results - but why is one correct and one wrong...

Regarding the heat disspation issue - it has been in the back of my mind and I hope to replace the Tufnol with aluminium at some stage in the future but my motors dont get very hot at the moment even when running cutting files for 8 Hrs straight. I will be watching them closely over the next few weeks though.

Have already fitted the Z and Y reduction and the difference in smoothness is remarkable. Not cut anything yet but will do so this PM. The smile on my face watching the Y car move back and forth so smoothly was almost as big as the first time I got the motors to move!
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  #324  
Old Wed 18 August 2010, 09:00
hennie
Just call me: Hennie #23
 
Roodepoort JHB
South Africa
Alan that material is probably a lot of $$$$ and do you get it in CT
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  #325  
Old Wed 18 August 2010, 09:28
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
I last bought Tufnol from: http://www.windingwires.co.za/distribution_network.html
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  #326  
Old Wed 18 August 2010, 09:31
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
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Yep its not cheap, as a comparison I bought two pieces of aluminium for this job in November last year - Cost R361.15, bought these two pieces of Tufnol end of July - Cost R 395.69 (both including VAT).

Its a nice material to machine and works well for things like spindle jigs (against a bearing) as a wear surface - for that I only use small pieces set into the base of the jig where it runs against the bearing. I have also made feed cogs for botteling machines from 10mm thick.

Available in Epping from Gartech Equipment 021 534 3388/9. I have seen couriers collecting from them for the Garden Route so if you need some they can get it to you.
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  #327  
Old Wed 18 August 2010, 09:42
hennie
Just call me: Hennie #23
 
Roodepoort JHB
South Africa
what sizes do you get it in?( I have a resin rep visiting next week,I might do a resin casting on my table for my spoil board)
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  #328  
Old Wed 18 August 2010, 11:58
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
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Not sure on sheet sizes but I think it is same size as plastic/perspex 2m x 1m.
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  #329  
Old Wed 18 August 2010, 14:50
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
All 4 motors now running on reduction drives - its smoooooth.

Found a few issues while testing. After changing the steps per setting I ran a test file and found that the Y dimension was a touch larger than the X dimension (0.2mm) so had to reduce the "steps Per" on the Y. Previously all 4 motors had the same setting so I was probably always cutting bigger on the Y - didn't check well enough when doing initial set up

I also notice that the Z motor and plate flexes quite a bit when plunging and retracting (at jog speed) probably due to the fact it is only fixed with one bolt at the bottom. (made more noticable now by the very much higher belt assembly) The other motor plates are of course held in place by two bolts either side of the pinion so no flexing is possible there.

I have run some files that I had issues with before (the oak hand held mirrors) and the result is much improved, the chatter marks are still there at about the same spacing but much shallower. I ran the job at the same speed as before (4m/min) which is faster than I currently run most of my work. I think the chatter marks are a function of bit rotation and feed speed but the reduction drive is better able to hold the apposing axes in the correct position therefore having far less effect. With the motors off it takes quite some effort to move an axis so once energised they are much better at holding position.
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  #330  
Old Wed 18 August 2010, 22:13
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Alan, if your racks fitted into each other (teeth meshed) along their whole length (before fitting to MM), then the "steps Per" must be identical.
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