Hi, Trying to remove the disc from a large disc/belt sander machine, where the rectangular Key has been driven deep back in the key way - so the disc is jammed on tight. I can't get at the back of the disc to try and knock it off. am I correct in thinking the best way to remove he key would to centre punch the visible end and drill successive larger holes in it? - then how to remove?
budgel,
Jul 6, 10:22pm
Drilling etc. sounds like an extreme solution to a problem you may not have. Most keys of that type slide out when the wheel/pulley or whatever comes off. If it is a friction fit with the rectangular key just stopping the disc from rotating on the shaft, a puller is the usual way to remove such things. A puller will have some means of attaching to your disc, and then a central thread that pushes on the shaft to wind in and move it off the shaft. This video is about removing a pulley without a puller, but the principle is the same:
CRC it first. Then. Can you hold the disc, or pull it towards you with the shaft facing you and tap on the shaft while holding the disc. Let the sander hang by it's own weight. Being careful to make sure the main body of the sander has somewhere safe to drop should the disc suddenly break free. That is if it is a portable sander. If it is not portable then CRC it first, get a bar to lever behind the disc and tap on the shaft with a bit of force being careful not to create any burrs or mushrooming the end of the shaft. It should just pop off.
muppet_slayer,
Jul 6, 10:34pm
If there is a thread on the end of the shaft, screw the nut on a few turns so that it sits just proud of the shaft end and tap on that gently.
muppet_slayer,
Jul 6, 10:35pm
and don't under estimate CRC, it works great for 'stuck' things.
marte,
Jul 6, 10:50pm
Often theres a grub screw over the key itself, undo that if there is. Heating the disc with a gas torch, and CRC the key. Drill & tap a hole in the end of the key & screw in a capscrew so you can pull the key out.
pandana,
Jul 6, 11:22pm
The problem re the puller idea. is we cant get a puller between the outer wheel and the dust collection cowling ( the sander is of a similar design to this one were the cowling(black) cant be removed until the disk is removed. https://www.machinery- house.co.nz/L107)
we did make a puller with 2mm flat arms. but nothing moved and we didn't want to risk breaking the disc because there is no way of getting the puller on the actual pulley on the back of the disc ( it only measures about 90mm across, where as the disc is 250)
hence we came to the idea of drilling out the key, . /.
Make sure you have CRC'd the key and shaft. Set the puller back up with moderate tension, as much as you had tried earlier, and then tap around the disc near the shaft with a hammer, and even try tapping on the end of the puller. Don't over do it just gentle taps.
tygertung,
Jul 7, 12:43am
Can you apply heat? Works quite well especially if you have an aluminium disc on a steel shaft as the aluminium expands more than the steel.
pandana,
Jul 7, 1:44am
yes, there is a screw in the center of the disc on this one too. (although its not direct drive like the one shown in your link) - already removed.
some of the other version I have seen the schematics for show a slot in the cowling to access a grub screw in the shaft behind the sander plate, but while this one has the slot, there is no screw in the behind the plate
pandana,
Jul 7, 1:47am
yes the first thing we tried before the puller was heating the allow plate centre. with a blow torch. I 'll have a go doing it all together.
Does it matter that the key has been driven right back, or is there no taper in there. ie: doesnt matter where the key is no increase in tension?
tygertung,
Jul 7, 2:33am
The key shouldn't affect it too much.
the thing to do might be to make up a plate puller which you can bolt together over the wheel and then have a bolt pushing on the shaft to push the whole thing off.
pandana,
Jul 7, 3:23am
ok, any chance you can show me a link to demonstrate what that is. is it different from the standard three legged bearing/ pully puller - google it but I am finding number plates you name it
tygertung,
Jul 7, 3:28am
I am thinking making a larger version of a bearing puller.
Sort of like that. Make it out of a bit of plate steel.
marte,
Jul 7, 4:16am
What Brand & Colour is it? Blue like in the link & hammercoat paint. Cast iron bed & table rest? Im quite interested to find out.
pandana,
Jul 7, 5:54am
Ah what a neat idea. but unfortunately. there is no way to get it behind the disc. as per earlier link the disc is fully inclosed in a dust collection housing. which can only be removed once the disc is off. the smaller pully is behind also
So, got the puller back on the disk, and this time seemed to be getting more movement until noted the edges of the alloy disk where bending up under the feet of the puller. emergency release! - as I suspected its two thing and far from the center to be a useful medium.
Then my mate had the idea. lets just slip the new belt over the alloy disk and be done with it. No. the disk is bigger than the belt. back to the drilling out idea. question is will it make any difference with the key gone!
marte,
Jul 7, 7:01am
I used to make a similiar sanding machine. Heavy duty & usefull for sanding metals. Ours were a tight fit on the shaft and held on by a grubscrew on a small flat on the shaft. We didnt use the disc option, it had a polishing pad setup on it instead. Sanding bed was vertical.
budgel,
Jul 7, 9:46pm
I think removing the key will probably only make a small difference, but who knows? I also think trying to drill out a steel key without running off into the aluminium will be difficult. Have you seen those V belts made up of individual segments? Maybe one of those could solve your problem.
cabrio1,
Jul 13, 8:53am
Drill 2 holes , just big enough to allow the puller legs to pass through. Or three if it's a 3 leg puller. Fairly close to the centre, maybe 1/4 way out. Then the legs will have more material to pull against. The legs pull best at 90 degree to the plate. Then put some tension on it. Put a hot air gun over the disc at the centre. Crank it up, bang. Get back to me on filling the holes up.
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