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

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?

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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.

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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.

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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…

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

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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.

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this one?

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

Quick sketch concept.

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.

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

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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.

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.

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.

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.

Pics are in this thread:

edit: link corrected, thanks to Gero.


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.

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


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.

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.


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