Has anyone ever made the motors on the sled? how to deal with extra chain?

aluminumwelder · August 11, 2018, 10:00pm

in the old forum their was a lady that made a sled with the motors on it. Dont’ recall her ever finishing her maslow build though. Can’t find the old thread on git hub.

Rotating t he motors on the sled should be possible with some laser cut piece of metal.

The other problem I can’t quite figure out though is how to deal with the extra chain. A derailleur or static pin to increase chain wrap would be needed and some sort of small cup/bucket OR spring wound take up spool

Any thoughts on how to accomplish this?

aluminumwelder · August 11, 2018, 10:03pm

this would eliminate about 22 feet of wiring and allow a relatively simple way to take all the electronics/sled inside while leaving a frame outside.

EdFeeney · August 11, 2018, 10:46pm

You could use a longer chain and return it to the top corner on an idler sprocket, with some sort of tensioner to keep it taut.

Jayster · August 12, 2018, 4:16am

The other problem is keeping the chains pointed to the center of the bit for triangular kinematics. If you went back to quadular (was that what it was called?) then I guess you could do it. Unless you could figure out a way to put the motors on a ring system…

jwolter · August 12, 2018, 12:55pm

You could mount the motors to a linkage / pantograph system.

aluminumwelder · August 12, 2018, 1:17pm

putting the motors on a ring system or pantograph system is the easy part for me.
Figuring out chain wrap is going to be more tricky IMHO.

kayaker37 · August 12, 2018, 3:09pm

this one?
https://github.com/pplante/maslowcnc-old-forums/blob/2ea7f0c6ec2b050cf8989163fcdce7ef0e9e2fe9/output/general/introduction-plus-headless.md

aluminumwelder · August 12, 2018, 3:51pm

Yes that is the post, however, the picture isn’t there any more and there seems to be no easy to way to find it, unless one wants to click through hundreds of images one by one? Anyways it’s not a big deal, she didn’t solve how to store the extra chain either. I think her idea was to have some small buckers under the 10 tooth gear to store the extra chain, but I really thing it needs some tension be spring loaded

EdFeeney · August 12, 2018, 4:17pm

Quick sketch concept.

aluminumwelder · August 12, 2018, 4:25pm

that is a great sketch. But why do you need so many take up pullies? The top corner of the frame is a good 70" to 90" off the ground so the weight has a very long distance to travel.

EdFeeney · August 12, 2018, 4:30pm

I didn’t calculate anything. I just presumed there will be a lot of take up.

blurfl · August 12, 2018, 4:49pm

Here are some design considerations that I see:

for a triangular linkage, the motors will need be free to move so that the line of the chain (a line halfway between the to- and from- chain paths and through the center of the motor shaft) intersects the center if the router bit. If I remember right, the smaller that radius, the better the chain stayed truly aimed.
does the point which represents the upper corner of the motor-sled-XY right triangle move as the sled travels to different corners? How to calculate exactly where it is and measure between the left- and right- ones?
the chain-to-cable splice cannot pass over the motor sprocket or the tensioning pulleys
the encoders on the motors will be much closer to the electrical noise of the router

All that aside, having the motors on the sled could make the whole machine easier to pack away and set up again.

aluminumwelder · August 12, 2018, 5:32pm

that’s a great question. I have to brush up on high school geometry! Probably the easiest way to make it sureproof is to have a 10 tooth sprocket right above the permanent chain attachment point. The further distance away the permanent point and the take up sprocket are then the more chance to introduce error?

looks like by getting rid of 25 feet of cabling this alternative adds a lot more chain and you are right sprockets would have to be used instead of pullies.

blurfl · August 12, 2018, 5:37pm

Doesn’t the tension cable become part of the equation as well? It adds some force to the motor position so it affects the pivot point too. The geometry of that corner looks complicated to me.

aluminumwelder · August 12, 2018, 5:42pm

maybe you are right, wil have to think about it more.

which is why I wanted to have the spring loaded “collectors” on the sled to begin with.
in that situation the top tanget point of the motor sprocket because the center line of the triangular kinematics. And their is only a single well defined top chain attachment point on the top beam.

kayaker37 · August 12, 2018, 6:23pm

Pics are in this thread:

github.com

pplante/maslowcnc-old-forums/blob/master/output/general/my-maslow-is-up-and-running.md

## My Maslow is up and running!
Posted on **2017-03-27 23:03:13** by **jessbussert**:

This is a photo of my first g-code run using a sharpie for a router bit.  Hey!  I don't wanna waste wood while I'm tweaking things, right?  https://imagebin.ca/v/3H5RMCHXBJAc



My machine looks a lot different from Bar's and so a little explanation might be in order.  Before Bar sent out the beta test kits I had already started hacking on the design.  I'm like that, ok?  https://imagebin.ca/v/3H5Rnz6K52xC



First off, I wanted my machine to be totally independent from the frame so that I could take the router, sled, electronics, and motors off the frame and pack them away in a reasonably sized package.  I wanted something that I could put in checked luggage or ship via UPS.  The reason for this is that I would like to be able to take the Maslow with me the next time I take a mission trip.  The last time I went somewhere (Haiti, after the earthquake) it would have been wonderful to have a tool like Maslow to help with the relief efforts.  Having everything together on the sled makes this a possibility.



Another reason I redesigned the sled was because I spend about 11 month s of the year traveling around the US in a big 'ol motor home.  I'm working as a traveling emergency room nurse and I take short-term contracts at hospitals around the country.  As such, I don't have a garage or much space to spread out while I'm on the road.  Having the Maslow reduced to a smaller, portable package just makes it easier for me to play with it when I'm away from home.



I also wanted to change the geometry of the machine to bring the math back to a simple trig function.  I was worried that the original design allowed for some unwanted torques since the router descends below the focal point of the chain triangle.  Now, to his credit, Bar has implemented some amazing black magic code to overcome this issue.  I was just hoping that if I went back to a basic triangle I could increase the cut rate without sacrificing precision.  In order to accomplish this I used two 12 inch diameter circular bearing races (http://www.rockler.com/low-profile-lazy-susans) mounted so they were each centered on the router bit.  I mounted the motors to these, each to its own bearing.  This setup allows each motor to swing around the router bit independent of the other motor.  It still remains to be seen it this will work or was just a lot of effort for minimal benefit.

This file has been truncated. show original

edit: link corrected, thanks to Gero.

Gero · August 12, 2018, 7:20pm

The concept and springs of this blinds rollers would do the job on taking the chains. A new and larger housing would need to be made.

Pic from Maslow without Stretchy String, bungies or elastic cord only blind rollers

The sled was build around a Lazy Susan I think. The first triangular before we had it in the software.

github.com

pplante/maslowcnc-old-forums/blob/master/output/general/my-maslow-is-up-and-running.md

## My Maslow is up and running!
Posted on **2017-03-27 23:03:13** by **jessbussert**:

This is a photo of my first g-code run using a sharpie for a router bit.  Hey!  I don't wanna waste wood while I'm tweaking things, right?  https://imagebin.ca/v/3H5RMCHXBJAc



My machine looks a lot different from Bar's and so a little explanation might be in order.  Before Bar sent out the beta test kits I had already started hacking on the design.  I'm like that, ok?  https://imagebin.ca/v/3H5Rnz6K52xC



First off, I wanted my machine to be totally independent from the frame so that I could take the router, sled, electronics, and motors off the frame and pack them away in a reasonably sized package.  I wanted something that I could put in checked luggage or ship via UPS.  The reason for this is that I would like to be able to take the Maslow with me the next time I take a mission trip.  The last time I went somewhere (Haiti, after the earthquake) it would have been wonderful to have a tool like Maslow to help with the relief efforts.  Having everything together on the sled makes this a possibility.



Another reason I redesigned the sled was because I spend about 11 month s of the year traveling around the US in a big 'ol motor home.  I'm working as a traveling emergency room nurse and I take short-term contracts at hospitals around the country.  As such, I don't have a garage or much space to spread out while I'm on the road.  Having the Maslow reduced to a smaller, portable package just makes it easier for me to play with it when I'm away from home.



I also wanted to change the geometry of the machine to bring the math back to a simple trig function.  I was worried that the original design allowed for some unwanted torques since the router descends below the focal point of the chain triangle.  Now, to his credit, Bar has implemented some amazing black magic code to overcome this issue.  I was just hoping that if I went back to a basic triangle I could increase the cut rate without sacrificing precision.  In order to accomplish this I used two 12 inch diameter circular bearing races (http://www.rockler.com/low-profile-lazy-susans) mounted so they were each centered on the router bit.  I mounted the motors to these, each to its own bearing.  This setup allows each motor to swing around the router bit independent of the other motor.  It still remains to be seen it this will work or was just a lot of effort for minimal benefit.

This file has been truncated. show original

The interesting pics are in -> Posted on 2017-03-28 14:07:53 by jessbussert :

Gero · August 12, 2018, 7:48pm

I have a 3d design of a 3 part slew bearing somewhere in my archives from those days. I need to dig.
The middle part would hold the router with a pendulum to keep it straight and the 2 outer part would hold the chains. Slew bearings can take the load and can be made sealed from dust.
I’ve frozen the concept as I have no idea who to manufacture the design.

aluminumwelder · August 12, 2018, 8:00pm

thanks but slew bearings tend to be expensive. and I already have a solution using cheap roller bearrings.
I will buy some of those blind rollers on ebay or some retractable cords and test them out.
I am not sure either one will hold about 9 feet of roller chain which is the minimum needed.

rbodelon · August 13, 2018, 10:34am

Gero,

The constat force is not enough, you need a powerfull constant forcé spring, I use it only with the strap.

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Has anyone ever made the motors on the sled? how to deal with extra chain?

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