How to drill rubber

[69supercj]

I've got some rubber stoppers that are about 5/8ths inch around and tapered and I need to drill one end of them with about a 1/4 inch hole but I've tried drilling rubber in the past and its danged near impossible to get a good hole thats not all chewed up. Any ideas?

 

[Daveo]

Ive heard freezing helps. Never tried though...

 

[rlitman]

Usually I've cored rubber stoppers with a tool for the job.
You could get a piece of thin walled steel tubing and sharpen it at the tip. Then chuck it in a drill and run it through the stopper held in a vise.

 

[gungatim]

we just drill them on a drill press when we were making them for carboy's to make wine (before you could buy them pre-drlled). 5/8? are they for test tubes? I've got a couple cases of tubes with stoppers I picked up at a sale, I could try drilling them and see. maybe they are softer than the white ones I am used to.

 

[ilovevocs]

If a twist drill wont work I would try a single flute end mill.

I would imagine you could even make one out of round bar that would do the job. I have made my share out of o1 drill rod. They are rather simple to make. High speed low feed and just take your time.

 

[DenisG]

Anyone who's worked in a lab has probably used a cork borer. They're also used on rubber stoppers.

 

[Oregon rock crusher]

These simple hand punches make very clean holes when spun with a drill. We use them on many different durometers and thicknesses of rubber, with and without reinforcing cords. Ed.

 

[69supercj]

Well I forgot to add a caveat to the scenario. These need to be blind holes not through holes.

 

[bullnerd]

Well I forgot to add a caveat to the scenario. These need to be blind holes not through holes.

DOH!

Some great info in this thread already.

Ill add to the chaos. My old boss used to drip antifreeze on rubber while grinding it with a tool post grinder in a manual lathe to make contoured drums for belt sanders. The finish was amazing.

 

[gungatim]

in that case just use a forstner bit.

I drilled a bunch of hockey pucks for machine mounts and the forstner bit did just fine for the countersink...

 

[WoodsTruck]

I use spent shell casings.

Rim fire casings don't tend to work that well since they have the lip at the base. Otherwise, chuck one up in a cordless drill and at slow speed slowly sharpen it on a flat file. Once sharp enough, use the drill to cut a hole through your material.

I typically use .223 - 9mm - .45ACP for most of my projects.

May not do what you want, but I pick up these casings at our gates where people shoot so the price is right.

 

[e36jon]

Depending on what sort of surface finish / accuracy you need in the hole, and how hard your rubber pieces are, I would go with grinding using a burr of some sort. My experience with drill bits in soft material is that they grab and pull the material, leading to really poor results. A carbide burr, used with a slow feed (the goal being to not compress / deform the material) should give you a nice result.

If it's hockey-puck hard, any woodworking tools should get it done, as mentioned above.

All of the above based on two projects trying to make shaped rollers out of soft-ish urethane.

 

[abachman]

As stated above, use forstner bits. They cut clean with a flat bottom.

 

[b_bueno]

The plug needs to be held in a two piece tapered holder (tapered hole and a base clamped) with the working end exposed. Drilling at a speed you make a continuous chip will work or a two flute endmill will let you make the blind hole flat.

 

[jhelrey]

I just use my bit from when I studded my snowmobile.

You can also make your own. I've in a pinch used a hollow tube, sharpened it on a bench grinder with a drill attached, and bam, a drill bit.

https://www.google.com/search?q=tra...UICSgC&biw=1600&bih=789#imgrc=vENd2BElCl374M:

 

[JMLangford]

in that case just use a forstner bit.

I drilled a bunch of hockey pucks for machine mounts and the forstner bit did just fine for the countersink...

as stated above, use forstner bits. They cut clean with a flat bottom.

^^^^^^^^ this ^^^^^^^^^




.

 

[4xdog]

Anyone who's worked in a lab has probably used a cork borer. They're also used on rubber stoppers.

+! on these. I have a full set in the top drawer (a relic from almost 40 years of working in polymer science). They're useful for all kinds of hole-cutting tasks, and perfect for cork and rubber stoppers, their original application.

I used one to cut the right-sized hole to put a grommet in the tonneau for my Triumph TR3. One of many things these are good for.

 

[E.rodz]

for a blind hole I would just heat up a punch or a rod that size and melt it in. put it in a drill press and use the depth stop I just use a propane torch to heat the rod.

 

[Kevin54]

Do not use a single flute end mill as it won't work. Even a multi-flute end mill will be iffy. I would try the sharpened tube method then tear the core out if you need a blind hole.

 

[theoldwizard1]

I would try the sharpened tube method then tear the core out if you need a blind hole.

A wood workers plug cutter (basically a sharpened tube), but you will still have to tear it out leaving a ragged bottom.