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ACME upgrade pictures for NEMA 17 install

Posted: Tue Mar 18, 2014 10:55 pm
by Improbable Construct
This is what it should look like all together
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Here is the bottom disassembled
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and here is the top disassembled
You only need to reuse one of the plates and the bearing.
The steel shim, other bearing block, and the stock spacers are not reused.
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Re: ACME upgrade pictures for NEMA 17 install

Posted: Wed Mar 19, 2014 2:13 am
by wz9v
Cool, just ordered one this afternoon, looks pretty easy to setup.

Re: ACME upgrade pictures for NEMA 17 install

Posted: Wed Mar 19, 2014 10:15 am
by RobCee
Nice to see your installation pics IC, your design is neat and tidy.

Apologies if this is not quite the correct place for a query like this, but it is pertinent to the upgrade and it's pictures.

I have been looking at my version using TR10x2 since it is simpler to obtain here in the UK than the US ACME rods.
While looking at ideas for supporting the bottom of the lead screw, I had a thought about how to reduce the overhang from the bottom bracket, which currently either blocks or narrowly misses the Spindle Carriage on the SO2. Ideally I would like to be able to remove the Spindle Carriage without having to remove the lower bearing mount on the lead screw.

Your (and my brutally plagiarised) design uses an identical flanged bearing to the top mounting point, which is fairly large (~25mm diameter) and needs some 'meat' around it to hold it in place. From my understanding of the design, the bearing itself is not hugely supporting the lead screw, just stopping it from wobbling around.
If we were to remove the bottom bearing (and housing plate) from the design and replace them with a chunk of Delrin and a small hole to capture the end of the lead screw. This would act as a low friction bearing surface for the end of the lead screw, not as free spinning as the bearing, but it would hold the end in place. Given this arrangement I believe that we would be able to drop the 'stick out' on the lower mount from about 15mm to maybe 7mm (from the axis of the lead screw).

Doing this would reduce the part count and should be pretty easy to achieve. Any thoughts on why it could not be done this way?

Re: ACME upgrade pictures for NEMA 17 install

Posted: Wed Mar 19, 2014 1:26 pm
by veng1
Although I'm way, way behind on getting a new Z-axis modification up and running, I've been thinking about how to eliminate the bottom bearing a bit.

If the Acme threaded rod was turned on a lathe to have a cup or cone shape on the end and a similar cup shape could be cut into the a plate located where the bearing plate goes now at the bottom of the carriage, then a single roller ball could be placed between the two cup shapes. Said arrangement would both locate the rod and provide thrust support for the threaded rod.

The question that pertains is how hard does the material need to be to last a reasonable time?

Re: ACME upgrade pictures for NEMA 17 install

Posted: Fri Mar 21, 2014 3:13 pm
by wz9v
Thanks for the pictures. Those should make it super simple to install the upgrade when it arrives today.

Re: ACME upgrade pictures for NEMA 17 install

Posted: Fri Mar 21, 2014 4:14 pm
by northbear
veng1 wrote:Although I'm way, way behind on getting a new Z-axis modification up and running, I've been thinking about how to eliminate the bottom bearing a bit.

If the Acme threaded rod was turned on a lathe to have a cup or cone shape on the end and a similar cup shape could be cut into the a plate located where the bearing plate goes now at the bottom of the carriage, then a single roller ball could be placed between the two cup shapes. Said arrangement would both locate the rod and provide thrust support for the threaded rod.

The question that pertains is how hard does the material need to be to last a reasonable time?
I have an Acme threaded rod without the bottom bearing which has worked well for me. I used a bit thicker mounting plate (3/8" aluminum) which was then counterbored for a bearing to set flush with the top. The bearing was captured by using four bolts with flat washers on the top, being sure the washers only touch the outside race of the bearing. The Acme rod has one end turned down to fit into the bearing (I used a 1/4" ID), then threaded for a 1/4" locknut, then turned down again to 5mm to fit in a standard 5mm x 5mm coupling. Everything is captured and only uses one bearing on the top. I am away from my CNC so I can't give you any pictures, but the CAD below probably explains it better anyways.
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Re: ACME upgrade pictures for NEMA 17 install

Posted: Fri Mar 21, 2014 4:15 pm
by northbear
Two additional pictures.
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Re: ACME upgrade pictures for NEMA 17 install

Posted: Fri Mar 21, 2014 4:37 pm
by cvoinescu
I considered that approach. I think it would work nicely, but, from a mass-production point of view, it has some disadvantages. The motor plate needs to be machined -- it can't be laser-cut out of sheet material. The Acme screw itself needs to be threaded, which is expensive compared to simply turning it down. For a one-off, it's a very good design, but if you want to make many, I think IC's approach is easier.

Re: ACME upgrade pictures for NEMA 17 install

Posted: Fri Mar 21, 2014 5:12 pm
by northbear
I have good connections with someone that does lathe work but don't have a contact for laser cut parts. And I was only making one, so this design worked out well for me. :mrgreen:

Re: ACME upgrade pictures for NEMA 17 install

Posted: Thu Jun 11, 2015 10:19 pm
by Caesar S
I'm just getting around to doing this. I already purchased the kit, Is there an assembly guide?