Cutting down bolts and pins

[kaszal]

I have a cheap Dremel-like rotary tool (from Maplins) and I was wondering if anyone could give me some tips on how to cut down bolts and hingepins? What type of attachment do I used and is it possible to cut a bolt down and preserve the end of the thread? Grateful for any advice. Cheers

[bodgit]

I always wind a nut down the bolt before cutting it then unscrew it after filing to true the cut end thread again.

[Dombrasky]

use the disc attachment,on bolts thread a nut on first,then when youve cut down the bolt undo the nut past the cut,this cleans the thread,then just dress sharp edge with a file,not sure on hingepin as i have never cut one down,they are hardened so might be tricky with a dremel,wear safety glasses if you can
-lol beat me to it, as above

[mark christopher]

High speed cutting disc will cut pins from titanium to silver steel. Use a grindimg some to clenched edges.

U shud av. Got a dremel tho......

[Bungleaio]

Safety glasses are a must, the discs break and the bits fly off at high speed.

[SlowOne]

Always hold whatever you are cutting in a vice and have a good grip on the Dermel so you cut it square. Choose the cut-off disc properly as well as the spindle speed.

For hardened steel pins, use a brown disc (usually thin) at about 20k rpm (for a new one) to 30k rpm (for a used one that has a small diameter) and don't push too hard. Let the cutter flow through rather than push through.

For Ti pins, use a black disc (usually thick) and drop the rpms to between 10k and 15k. Give the tool a little push, but be very careful of heat build up as Ti is soft and can clog the wheel easily.

In either case, if the metal changes colour when you're cutting it, you have softened it and it will be weaker in that area. Providing that the nut goes past the softened end, it'll be fine. Ti will be OK, but try not to use the very end of the bolt or pin to take too much load.

Practice on a scrap bolt, cutting about 10mm off at a time. One thing to watch - if the cheapo Maplin tool slows down appreciably while cutting, you'll always have problems with a poor cut and overheating of the part and the tool. If it does that regularly, it won't last long. I've had two Dremels in the last 35 years, and the first one died because it ran out of copper on the commutator due to 28 years of excellent service, most of that building slot-race chassis!! HTH

[kaszal]

That's great. Thanks for the detailed advice.