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Tubular Drive

by rweaving, published

Tubular Drive by rweaving Jan 9, 2012

Description

This is a tubular drive mechanism. It is designed to use 1/2 inch aluminum conduit. This is a work in process, and I am already working on a newer version that will use dual rails. I think that this type of mechanism will work well as an linear axis drive mechanism when combined a stepper motor, and magnetic linear encoder would provide high accuracy large scale positioning.

Tubular Drive Test Fixed Drive http://www.youtube.com/watch?v=k0G8B77UOJs

Tubular Drive Test Fixed Conduit http://www.youtube.com/watch?v=70dTRN7zSpU

Recent Comments

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Ive been interested in using conduit for some projects by my main worry is the accuracy of the pipe itself. Have you tested how straight the conduit is?

You only need three wheels.

On the driven side use one, and make it sit between the opposite two (like a triangle). Make it spring loaded.

Three wheels like that means it automatically aligns to the pipe and applies pressure, which is a bit of a pain with four wheels.

The drive rollers have adjustment, the bolts on the top push down on the wheel bolt. I dont know if rubber cement would work well. I'm going to be looking a using plasticoat.

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Instructions

Print the parts with 75% infill 3 shells. Print the spacers at 100% infill. This uses standard 608 skateboard bearings for the wheels. Brush the sides of the wheels with acetone and sandwich the bearing between them. After the wheel has setup and is hard brush the surface of the wheel with acetone, this will help to bond the abs even more.

Ive been interested in using conduit for some projects by my main worry is the accuracy of the pipe itself. Have you tested how straight the conduit is?

You only need three wheels.

On the driven side use one, and make it sit between the opposite two (like a triangle). Make it spring loaded.

Three wheels like that means it automatically aligns to the pipe and applies pressure, which is a bit of a pain with four wheels.

You might be able to increase the grip on the tubes by coating the surface of the rollers with rubber cement. An adjustable tension knob/bolt on one of the rollers would help as well.

The drive rollers have adjustment, the bolts on the top push down on the wheel bolt. I dont know if rubber cement would work well. I'm going to be looking a using plasticoat.

This could be good printable alternative to linear bearings, even with traditional belt-driven movements. As far as driving is concerned, I suspect there wouldn't be enough friction to reliably position printing surface due to slipping. On the other hand, if you build reliable absolute positioning sensor with magnetic strip or just current sensor, if could be mitigated, but it would require firmware changes.

The friction is pretty high, more then I would have thought. The drive has bolts so you can increase the wheel pressure. As soon as my stepper motor arrives I will do some testing to determine accuracy. I also ordered a linear encoder, so I should be able to do some step corrections. I will have to look at what changes I will need to make to the drive code.

Did you do anything to the curved surface of the drive roller to smooth it down or make it more accurate? I tried something similer to this and could never get it to roll smooth enought on the shaft due to runout and imperfections in the printed surface.

I brushed it with acetone, this helped to bond the printed abs. After the surface was dry to the touch but still soft I rolled it back and forth on the conduit. This rolls extremely smoothly.

nice. i could use this in an automated overhead gantry with a camera bolted onto it as a documentation aid. will have to think about it tho.

In the mean time, what are you using for a control unit?

I think it work well in a gantry type application. You can stiffen aluminum conduit by inserting oak dowels the inside diameter of the conduit to achieve long runs. I'm not using anything at the moment to control it. I was just powering it off of my bench power supply for the videos. My stepper motor version will use the Makerbot stepper driver connected to an Android ADK.

I an see some very interesting uses for this great device..

Thanks for sharing

8-) 8-) 8-)

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