Abrasive Coping Set-ups

[Will Neide]

Abrasive coping.....I'm considering trying to set-up an abrasive coping rig, and am curious what pitfalls I should avoid. I know some are successfully doing this. There appears to be a few commercial set-ups that can be used, or modified to work well, but they seem costly and excessive. Not that I'm trying to keep it cheap, but I'd like to keep the scope of the project reasonable for bicycle tubing.

Some of the "pros" I see are cheaper belts, cleaner cuts, better on thin metal, and speed. Also, smaller footprint than a mill AND you can still use it as a belt sander.

The only "con" I can think of is more dust/air particulates.

Has anyone tried both and prefer one way over the other?

Any input would be appreciated. Thanks!

[Clockwork]

https://www.flickr.com/photos/clockw...-bz1y5z-by55Jr

https://www.flickr.com/photos/clockw...-am3geN-akZsLz

https://www.flickr.com/photos/clockw...-am3geN-akZsLz

My favorite tool. It was made by Mark Zeh and is fairly simple. Cuts perfect miters every time and it doesn't matter if you're using really hard tubing.

[rauce]

I like this concept as well.

I saw this example on youtube a little while ago:



There always seems to be a few of these big box store 4x36 belt/disc sanders on the local classifieds for cheap.

[edoz]

I don't think the belts will last as long as a holesaw, but I have no numbers to back that up. Also, I doubt you'd be gaining any time over doing it with a file.
The dust consideration is a big one, if you've ever worked in a place where a lot of abrasives are used, you know the dust will get into everything.

[Clockwork]

I get about 3 frames out of one 36 grit belt. The dust isn't much of a problem because the particles are very big and 95% fall on the unit base. It's a lot faster than hand mitering--10 seconds to set the angle and 10-20 seconds of cutting.

[Eric Estlund]

If I were to do it, I'd be tempted by an industrial unit designed for larger/ longer wear belts and with the ability to attach some sort of vacuum or containment system.

[back40]

I built a mill based abrasive miter system about 10 years ago. Originally it was for use with True Temper S3 tubing which tended to catch on the hole saws I used. Now, building in carbon it's really the ideal solution for me. I can make whatever size mandrel I need on the lathe. Very little load on the tube while cutting.

The only issues I've run into are the dust, grit and belt tracking as the cut moves across the belt and heats up. A shop vac with 0.3 micron filter seems to deal with the dust issue if I suck it away as the cut takes place.

Tube Sander 1.jpgDT Miter.jpgCSMiter2.jpgTubeSander2.jpg

[Mark Kelly]

The only issues I've run into are the dust, grit and belt tracking as the cut moves across the belt and heats up. A shop vac with 0.3 micron filter seems to deal with the dust issue if I suck it away as the cut takes place.

Is the idler pulley crowned? If not that might help with the tracking issues.

[Clockwork]

If I were to do it, I'd be tempted by an industrial unit designed for larger/ longer wear belts and with the ability to attach some sort of vacuum or containment system.

I have one of those at my day job and the feeding lever thing is not very controllable. The X-Y mill table for feeding is key. I don't think there's anything off-the-shelf that will work well for bike tubes.

[Eric Estlund]

Yeah- I make no endorsement of that one- it was chosen simply as a visual example of what I was talking about.

The key (in my mind*) is the longer belt. This one, for example, uses a 6" x 78" belt.



*This would be for my uses- as it is I am quite happy with mills and saws for my needs.

[back40]

Is the idler pulley crowned? If not that might help with the tracking issues.

It's crowned and adjustable one one end. I think it comes down to overall tension (too high or too low won't work) and differential heating during the cut.

[afwalker]

Pic of my collector for vsalon topic by Andy Walker, on Flickr
here I'm using the big Noga mount with an Stauff clamp adapter for the vac hose. Works well for dust collection. I would think this would work well for abrasive setups, maybe I will try to mimic back40s awesome solution for abrasive mitering. Inspired by Tom Lipton of Oxtools. Stauff Gr-5 like this: Lot of 2 Stauff Type GR 5 Hydraulic Clamps Green 1 5" No Screws | eBay
andy

[Mark Kelly]

It's crowned and adjustable one one end. I think it comes down to overall tension (too high or too low won't work) and differential heating during the cut.

OK, just wanted to check you had it covered.

If the problem is caused by differential thermal expansion the belt should shift towards the part that's being cut (eg downwards in your 2nd pic).

As an aside: I used to work as a process engineer at a big food plant. We used to get runaway differential thermal expansion in the paired rollers that flaked breakfast cereal: the rollers have a large diameter but a small gap to squish the cereal, if one part of the roller heats up it more than the others it expands, closing the gap, increasing the heat produced at that spot and setting up a positive feedback loop. This despite the internal cooling channels in the roller.

[abbeyQ]

Anybody know if the heat involved in using a setup like this creates an issue with the air hardening steels that are common in frame building? Does anybody make a setup like this that's liquid cooled?

[Mark Kelly]

Given that you are cutting the part that is going to be welded or brazed, I can't see it making any difference.

That being said, a waterproof belt and water cooling or a misting system would be a good way of combatting dust, too. Waterproof belts in appropriate sizes are available: my current favourite belt, the Norton Bluefire, is one such.

[Clockwork]

Only the thin "ears" of the miter get hot enough to turn a little red.

Regarding belt slip, the belt is pretty tight and the rollers can be fine-tuned with set screws on the mounted bearings. I haven't touched these in years, though. Otherwise, your cutting for so little time that the belt or steel rollers don't heat up at all.

[shrodinger]

Anybody know if the heat involved in using a setup like this creates an issue with the air hardening steels that are common in frame building? Does anybody make a setup like this that's liquid cooled?

Anybody know if the heat involved in using a setup like this creates an issue with the air hardening steels that are common in frame building? Does anybody make a setup like this that's liquid cooled?

In my work country Grit (fein) Germany Manufacture a machine which is controllable for both speed via an inverter and has a water cooling unit.

The use of this water cooling unit is useful for maraging steel and stainless steel titanium and composite materials all of which can be safely processed ,the water running away to a tank with filtration. A lot of vehicles manufactured here use exotic construction

Titanium is cleaned in nitric acid to remove industrial scale, grease and anything picked up or impinged in the Fisch Mund, this has been proven in aerospace grinding applications.

The inverter speed control Is useful as differing materials required are reliant on surface speed and destruction of their abrasive material is dependant on new sharp edges being created as the abrasive wears ,this is intentional

As Someone above pointed out those machines illustrated in other posts are clones of the Almi 100 and are using 100mm x 2000mm belts ,As someone else asked the roller drive in these units is a Polyurethane coated aluminium and is indeed crowned where it is driven, it is driven by a 3kw motor
we trialled one of these units.

The Grit Machinen is using a flat uncrowned contact wheel but has a much more accurate tracking system for the belt as it a seperate ad on to the front of the main machine.

Long belts over 2 m give a much longer life ,at my company literally hundreds of notches from one belt before change ,brown belts are aluminium oxide and relatively useless for abrasive notching but are intended for deburring not high speed metal removal.

Belt colour is used as an indicator of abrasive material (ceramic ,zirconia alumina, etc) however colour is also an indicator of resin binder lubricant and also wether the belt is waterproof so cannot be relied upon completely , Belts also have a pressure rating and grit rating which combined correctly will give spectacular metal removal rates and finish and also will reduce heat build up in the material.
the poorest grinding comes from the brown ordinary aluminium oxide and may be the reason some dismiss abrasive grinding as poor compared to other methods

below is a link showing drive wheels and belts.

Friedrich August Picard GmbH & Co. KG - abrasive belts with zirconia aluminium oxide

whilst we are in germany the Hermes and Norton Belts are the best we tried but they are not made here.

The downfall of the units is the X Y TRAVEL and clamp, I recall making tube clamps and an angled top plate for light use you will never wear them out however, if you clean them or cover them to reduce dust ingress, do not grease them either Grease will pick up all foreign matter.

Torben

[rauce]

Is this the machine?

[Will Neide]

It sounds like the X-Y movement and ability to safely clamp the tube are two the most important features. A few of the industrial models seem to fit the bill in regards to size and power, but lack decent X-Y movement. Joel's set-up seems pretty straight forward.

I hadn't considered belt material, so that's good to know.

Any thoughts on this unit? Shop our G0767 - Abrasive Tube Notcher at Grizzly.com

[edoz]

It sounds like the X-Y movement and ability to safely clamp the tube are two the most important features. A few of the industrial models seem to fit the bill in regards to size and power, but lack decent X-Y movement. Joel's set-up seems pretty straight forward.

I hadn't considered belt material, so that's good to know.

Any thoughts on this unit? Shop our G0767 - Abrasive Tube Notcher at Grizzly.com

MY thought on that unit is that it's the price of a decent used mill, and a mill is a lot more useful when you aren't coping tubes than a dedicated coping machine. I've even seen a mill set up as an abrasive coping machine, but thinking about all that grit in the ways made me cringe.