Trimming the drive shaft on a Mashima can motor

[ben mason]

Can anyone suggest a good way to remove the rear end of the drive shaft from a Mashima can motor? So far the best results I've had were with a diamond file although the hardness of the steel shaft has already worn one out in so doing and they aren't cheap. I'm wondering if it would be better done with a Dremmel (or similar) mini power drill with a diamond disk but I don't want to invest in one only to find that it won't work! Thanks and Best Wishes from Ben.

[DougN]

A dremel with a cutting disc has always been the way that I have done it. I usually leave a good 1 to 2mm hanging out though so as to not go too close to the bearing.

[David Knight]

The Dremel tool with a regular cutting disc ( made of an abrasive of some sort, probably carborundum) will do the trick. It might be advisable to wrap the motor in foil so as to protect the innards from the abrasive particles and metal filings generated during the process.

HTH

David

[Will L]

The Dremel tool with a regular cutting disc ( made of an abrasive of some sort, probably carborundum) will do the trick. It might be advisable to wrap the motor in foil so as to protect the innards from the abrasive particles and metal filings generated during the process.

That's the way to do it. Though foil? I usually use masking tape/selotape. Remember to leave enough shaft so that you can get a pin chuck on it when its installed on the chassis so you can turn the wheels by spinning the motor when wheel cleaning or fault finding.

Will

[allanferguson]

What you need to watch is a possible build up of heat from the cutting, especially if cutting close to the motor. Frequent pauses! Also eye protection is essential (as if I would need to tell this group!) I have done a number this way with no problems.

Allan F

[David Knight]

That's the way to do it. Though foil? I usually use masking tape/selotape. Remember to leave enough shaft so that you can get a pin chuck on it when its installed on the chassis so you can turn the wheels by spinning the motor when wheel cleaning or fault finding.

Will

I got the idea from a Tim Shackelton article in MRJ. The advantage is that you can mould the foil to cover all the bits you want covered and leave no tape residue behind. There may even be a little heat sink effect although this would be minimal.

Good point about leaving a stub.

Cheers,

David

[ben mason]

Thanks to everyone for answering. I now have a dremel on the shopping list.

[Paul Willis]

Thanks to everyone for answering. I now have a dremel on the shopping list.

Carborundum slitting discs *will* shatter, no matter how careful you think you are being.

As well as always using eye protection, getting a bulk pack from Eileen's is always a good idea, just so you don't break the only one that you have at 10pm on the Saturday night before a bank holiday...

HTH
Flymo

[Chris Mitton]

At the risk of stating the bleedin' obvious, don't make the (expensive!) mistake I once made - check carefully which end you're cutting off!
Regards
Chris

[Jol Wilkinson]

A slightly different approach that has always worked for me.

Wrap the motor in masking tape, with both shafts sticking out. Fit the "retained end shaft" into an ordinary electric drill. Whizz up to speed and with a good quality triangular needle file (a diamond coated file would be ideal but I have found a Vallorbe one works well), "score" the shaft to be discarded at the cut off point. Keep going until about 1/3rd way into shaft and through the case hardening. Now break/snap off end of shaft.

After the comments about sticky residue from tape, how about wrapping the motor in cling film?

Jol

[Re6/6]

Thanks to everyone for answering. I now have a dremel on the shopping list.

As you're going to get a Dremel I would advise getting a diamond slitting disk with it instead of the 'shatterable' carborundum variety. I binned all mine after one disintegrated spectacularly. You won't ever regret buying a Dremel. I use mine constantly. For some strange reason the large 40mm always seems to work better for me than the smaller sizes. They are also generally thinner than the carborundum variety. I've actually trodden on and bent one and and it hasn't broken.

[Will L]

After the comments about sticky residue from tape, how about wrapping the motor in cling film?

No reason why not, but I can't say I've ever had a problem with sticky residue. Tape is only on for a couple of minutes, and stick residues are usually associated with leaving tape in place for long periods of time.

I queried foil because it doesn't necessarily seal against all entry in, but in all probability making the effort with anything is all that is really needed and perfection is not an issue.

I've never had a slitting disk shatter when spinning in the drill, probably depend on how much stress you put on them. I usually brake them by misuse in other ways! I certainly wouldn't go without the eye protection.

Will

[DougN]

Will is that when you go to put the dremel down on the desk after use and it has stoped spinning... only to have it go ping when it hits the desk surface... I have done this way to many times. Some have been when the dremel disk has hit the edge of the desk when I have moved something and the dremel has tried to fall off!

[Will L]

Will is that when you go to put the dremel down on the desk after use and it has stoped spinning... only to have it go ping when it hits the desk surface...

That sort of thing.

Will

[Philip Hall]

Another use for a cutting disc is for trimming the bosses on coupling rods. It takes ages doing it with a file. I have do do quite a lot of this as almost all RTR stuff that I convert has holes that are too big, and after bushing there is room to cut them down a bit. I set the drill going quite slowly, so I don't get sprayed with the dust, and work the edge of the disc around the boss and the oil boxes until I get the shape I want. I find the carborundum discs are better for this as they seem to be a little thicker than the diamond ones. And yes, they do shatter, although almost all of my breakages have been when I've knocked the drill off its hook and it falls on the bench. As it does with expensive small drills in the chuck as well...

Philip