Home made abrasive sticks?

[Walney Col]

Hi.

Has anyone ever tried coating surfaces in Aluminium oxide powder to make their own specialised abrasive sticks/wheels/pads/whatever?

I'm in need of some abrasive sticks ranging 50mm to 75mm in length and 3mm to 8mm in diameter that I can stick in a litttle spindle motor and use to sand the inside of very tight curves typically in material less than 12mm thick.

My questions is; if you've ever made such a thing what sort of adhesive did you use to bond the aluminium oxide powder to your substrate and what sort of substrate did you use?

 

[Phil Pascoe]

I can't help for round ones, but for flat ones get emery boards (for fingernails) at pound shops - £1 for 25.

 

[Walney Col]

Thanks phil but I already have some of those. What I'm after here is a way of making abrasive tools that have specific profiles which means finding a way of gluing the aluminium oxide powder directly onto profiles that I've made myself.

 

[Spindle]

Hi

I can't help with complex profiles but for cylinders if you cut a slot down the axis of the cylinder you can put pieces of wet and dry / aluminium oxide paper centred into the slot and the rotation of the spindle will wind them onto the cylinder - no other fixing is necessary.

A bit like this but the mandrel should be placed in the centre of the abrasive strip

Regards Mick

 

[rafezetter]

It depends I guess on the hardness of the material you are sanding; you might get reasonable results by laying down a thick coat of oil paint / varnish and flooding the area with the powder.

for smaller areas you might get away with some epoxy resin glue like araldite and again pushing that into a container of powder.

it'll be rough to start with *ahem* but the grading may even out along the profile with use.

There's also needle diamond files (as oppose to the metal crosscut types) that have some different profiles, you could cut the pointy tips off to use in blind holes

 

[Random Orbital Bob]

I've never done this myself but I know a chap who has. He used to turn dowels to the desired diameter and then glue flexible sandpaper type abrasives on to them. Another method that occurs to me that might be worth trying is that you can buy Velcro backed aly oxide abrasives (Rhyno-Grip for one) which could be stuck on to a sticky back Velcro strip that itself has been wound onto a suitably dimensioned dowel or spindle. I'm thinking of cutting both the sticky back Velcro and the rhino grip into thin strips, say about 10mm wide and winding on much like you would wind on the loading for a drum sander ie in a spiral twist.

I guess the combination of sticky back Velcro and rhino grip would add a bit to the diameter of the spindle so you would need to compensate for that by turning it narrower than final required diameter.

I mention that sticky back Velcro stuff because it is unbelievably sticky and I'm sure it would hold really well. The Rhyno grip abrasive is almost impossible to pull off once its stuck to the Velcro so that solution would likely be very robust. Not sure if the abutting edges would catch while sanding....would need to experiment a little.

 

[Walney Col]

Thanks for the suggestions guys.

I think I'll try the araldite approach first as that offers the opportunity to stick the abrasive to things other than a straight rod. The slit idea I've already tried and it's ok(ish) for the larger ones (6 or 8 mm dia) but pretty hopeless (at least for me) on rods as thin as 3mm as a single turn of paper keeps slipping off but bulk of more than one single turn of paper takes them larger in diameter than I want. Likewise the velcro backed stuff. It's just too bulky for the small diameters I need.

 

[Random Orbital Bob]

It does strike me that a suitably sized range of needle files sound like the solution from how you describe the problem.

 

[Walney Col]

It does strike me that a suitably sized range of needle files sound like the solution from how you describe the problem.

I've not been able to get satisfactory results with a needle file, they clog too easily.

 

[Phil Pascoe]

Chainsaw files are coarser.

 

[Walney Col]

Chainsaw files are coarser.

That's an idea. Thanks. I've never seen one but it might help with the straight bits.

 

[rafezetter]

It does strike me that a suitably sized range of needle files sound like the solution from how you describe the problem.

I've not been able to get satisfactory results with a needle file, they clog too easily.

try the diamond file versions - they arn't cut, they have embedded abrasives

 

[Phil Pascoe]

Chainsaw files are coarser.

That's an idea. Thanks. I've never seen one but it might help with the straight bits.

You can get small range of sizes for different sized teeth. From about 3mm to 8mm, I think.

 

[powertools]

If your material is normally only 12mm thick I don't understand why you would want a shaft up to 75mm long at 3mm diameter I think that could cause a problem.
I have overcome this sort of problem when wanting to sand very small internal curves by using a split pin and feeding abrasive paper through the split and wrapping it around the pin leaving enough of the pin with no paper in it to insert it into the chuck of a flexi drive.

 

[Phil Pascoe]

Good point of course about the length - any file would have to be cut/broken.

 

[Walney Col]

I wouldn't mind having to cut the chainsaw files down, but my guess is that being steel they'll be rigid enough to use as they are. I've just ordered some 3mm and 4mm ones to play with.