G11/gm8 direct drive to NEMA17 motor adapter plate


ybaransky
 

Hi - I am looking for a file I can 3d print an adapter plate to attach a NEMA17 motor to a Losmandy G11 or gm8. I could only find adapters where belts and wheels are used. Those are more complicated and I prefer the simplicity of the direct drive version (I am using 400 step motors). If someone would print up a few for me (for a small fee and postage) I would do that instead.
Also... What material is best to use? I am planning on using ABS, but would rather have votes from real users. Thx -yurij 


Martin Chapman
 

I have the files, will dig them out as soon as I can.

On Mon, 15 Aug 2022 at 16:32, ybaransky <ybaransky@...> wrote:
Hi - I am looking for a file I can 3d print an adapter plate to attach a NEMA17 motor to a Losmandy G11 or gm8. I could only find adapters where belts and wheels are used. Those are more complicated and I prefer the simplicity of the direct drive version (I am using 400 step motors). If someone would print up a few for me (for a small fee and postage) I would do that instead.
Also... What material is best to use? I am planning on using ABS, but would rather have votes from real users. Thx -yurij 


Martin Chapman
 

I had a friend print some as my printer is a pain, that satisfied me that it would work. Then I found a chap in Bristol, (UK), who machined them for me in Aluminium.  Very fast and cheap. You will need to think about the couplings, they are imperial sizes on the mount but a 5mm shaft on the motor. You can probably find a spiral coupling, I just ran a 5mm reamer into one half of my existing coupling. Ideally you will want to pet a spacer under the dec axis plate, to stop the head from colliding with the mount, I think it’s about 45mm. ( I have the file for this also), I tried it out using 10mm nuts slid over longer bolts, it worked so well I never got  around to making the proper spacer.  Have the 400 step motors, when I first did it I could get 4 deg/sec but since upgrading my software I can now only get 2. But that’s better than using the setting circles.

On Mon, 15 Aug 2022 at 17:03, Martin Chapman via groups.io <smartacus32=gmail.com@groups.io> wrote:
I have the files, will dig them out as soon as I can.

On Mon, 15 Aug 2022 at 16:32, ybaransky <ybaransky@...> wrote:
Hi - I am looking for a file I can 3d print an adapter plate to attach a NEMA17 motor to a Losmandy G11 or gm8. I could only find adapters where belts and wheels are used. Those are more complicated and I prefer the simplicity of the direct drive version (I am using 400 step motors). If someone would print up a few for me (for a small fee and postage) I would do that instead.
Also... What material is best to use? I am planning on using ABS, but would rather have votes from real users. Thx -yurij 


Pete
 

I tried 3D printed ones and ended up making mine from 1/4" steel plate.  
I purchased new Oldham couplers from Losmandy which I drilled out (the are brass) from 3/16" to 5mm.  Then I cut the Nema 17 shafts to length. I drilled the two motor plat mounting holes a little large so that I could align the motor perfectly in line with the worm.  Rotate it and the Oldham coupler does not slide in either plane.  I'm using 5160 stepper drivers and 32 microsteps so I do not drop steps.

I kept slew speed to 2. degrees/sec so as not to  strain the worms.  It works perfectly.


ybaransky
 

Mark - thank you. If you find the model that would be great. I didn't think the axis would bump into the motors (haven't seen any posts about this), but I have that RA extension, so hopefully that will fix things for the G11. 
What was the cost of the aluminum ones and what was the thickness? 

Peter - thank you for the info. 1/4" steel seems excessive. Do you think 1/8" aluminum would be good enough?

-yurij 


Chad Gray
 

Do not be too afraid of mild steel.  It works pretty easy with a jig saw (blades for metal) drills (stepper drill bits) and band saws.  I use a portable bandsaw and i built a table for it.  Lots of plans out there.

I was pretty surprised.



On Mon, Aug 15, 2022 at 2:58 PM ybaransky <ybaransky@...> wrote:
Mark - thank you. If you find the model that would be great. I didn't think the axis would bump into the motors (haven't seen any posts about this), but I have that RA extension, so hopefully that will fix things for the G11. 
What was the cost of the aluminum ones and what was the thickness? 

Peter - thank you for the info. 1/4" steel seems excessive. Do you think 1/8" aluminum would be good enough?

-yurij 


ybaransky
 

Seems like overkill. And aluminum seemes easier to work.
-yurij 

On Mon, Aug 15, 2022, 3:15 PM Chad Gray <rchadgray@...> wrote:
Do not be too afraid of mild steel.  It works pretty easy with a jig saw (blades for metal) drills (stepper drill bits) and band saws.  I use a portable bandsaw and i built a table for it.  Lots of plans out there.

I was pretty surprised.



On Mon, Aug 15, 2022 at 2:58 PM ybaransky <ybaransky@...> wrote:
Mark - thank you. If you find the model that would be great. I didn't think the axis would bump into the motors (haven't seen any posts about this), but I have that RA extension, so hopefully that will fix things for the G11. 
What was the cost of the aluminum ones and what was the thickness? 

Peter - thank you for the info. 1/4" steel seems excessive. Do you think 1/8" aluminum would be good enough?

-yurij 


Pete
 

Nope.  I 3D printed them and then made them in 1/8" aluminum.  Neither eliminated wobble.  I had some 1/4" steel plate in the garage and took my side grinder to that and then used  a Home Depot Milwaukee Hole Dozer in my cheapo drill press and then finally drilled the mounting holes.  Make sure you get the right diameter for your Nema motor. It took about 90 minutes to do although I did make about 6 before I got it right.  I wanted to use the existing G-11 gearbox mounting holes and the have the Oldham couplers not wobble.

A36 carbon steel is very easy to work with.  Obviously aluminum is softer but i really think that you need 1/4" - even if it is aluminum.   The 3D plates i printed were thicker than 1/4".


Pete
 

Here is a link to my Google Photos G-11 OnStep build library.  There are comments on most photos that explain what I did and why.  


Martin Chapman
 

Having trouble locating the models and drawings, probably on my works machine but I’m on long term sick leave at the mo, may be able to sneak onto the system tomorrow. I paid about £65 for 2, less than half the quote I got locally, I believe mine are 8mm thick, could be 10

On Mon, 15 Aug 2022 at 19:59, ybaransky <ybaransky@...> wrote:
Mark - thank you. If you find the model that would be great. I didn't think the axis would bump into the motors (haven't seen any posts about this), but I have that RA extension, so hopefully that will fix things for the G11. 
What was the cost of the aluminum ones and what was the thickness? 

Peter - thank you for the info. 1/4" steel seems excessive. Do you think 1/8" aluminum would be good enough?

-yurij 


Martin Chapman
 

1/8” should be fine, they are not under stress.

On Mon, 15 Aug 2022 at 19:59, ybaransky <ybaransky@...> wrote:
Mark - thank you. If you find the model that would be great. I didn't think the axis would bump into the motors (haven't seen any posts about this), but I have that RA extension, so hopefully that will fix things for the G11. 
What was the cost of the aluminum ones and what was the thickness? 

Peter - thank you for the info. 1/4" steel seems excessive. Do you think 1/8" aluminum would be good enough?

-yurij 


Pete
 

1/8" steel, yes.  1/8" aluminum maybe but, I like steel better.


ybaransky
 

I am surprised that even 1/8" aluminum might not be rigid enough. 
1) There are lots of examples of 3d printed brackets, maybe phd2 is able to guide out whatever small flexture is introduced so it's not noticed? 
2) the stock losmandy gear/drives are attached with what looks like stamped thin metal, much thinner than 1/8" and no one has identified that as a issue 
Thx
-yurij 


George Cushing
 

6-7mm by 50mm aluminum bar.

image.png


George Cushing
 


And mods needed for a flex coupling.
image.png


Martin Chapman
 

It’s not really the rigidity that’s important, the 2 lower mounting screws for the motors need to be recessed as they are almost in line with the mounting plate holes that hold the plate to the mount, so you can’t have the screws standing proud, if you see what I mean? I made my motor mounting holes counterbored, rather than countersunk countersunk holes are abhorred in engineering. Hope this makes sense?

On Tue, 16 Aug 2022 at 12:58, ybaransky <ybaransky@...> wrote:
I am surprised that even 1/8" aluminum might not be rigid enough. 
1) There are lots of examples of 3d printed brackets, maybe phd2 is able to guide out whatever small flexture is introduced so it's not noticed? 
2) the stock losmandy gear/drives are attached with what looks like stamped thin metal, much thinner than 1/8" and no one has identified that as a issue 
Thx
-yurij 


ybaransky
 

Martin - makes total sense now. thanks for clearing that up. -yurij 


ybaransky
 

George - thx for the drawings. Very useful. -yurij 


gjores@...
 

hi
just what I needed  thanks


Jay LeBlanc
 

I experienced very bad runout using flex couplings that fasten directly to shafts with setscrews. Use clamp style instead!
-Jay-

On 8/16/2022 7:10 AM, George Cushing wrote:


And mods needed for a flex coupling.
image.png