Results 31 to 45 of 91
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22nd Jul 2018, 12:35 AM #31
Hi Gunnaduit, Guys,
The trick in shifting stuck grub screws in pulley hubs and the like, is to blast the hub with heat very rapidly. This is where the oxy acetylene or bead of weld comes in. The idea is to cause the hub to expand before the shaft has had had a chance to. Once the heat has started to travel into the shaft it is too late. All you can do is let it become cold again. Water or ice on the shaft can help.
Since you say you have drilled the grub screw out, I do wonder if you have not actually got the whole diameter over the threads clean. If there is any shell left in the hole that may be preventing the pulley from moving. M8 is a big grub screw !
Another thing you could try, assuming that you really have cleared the grub screw out, is to try tapping the pulley further onto the shaft and see if it moves, but if you can support the other end of the shaft.
HTH.Best Regards:
Baron J.
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22nd Jul 2018, 09:58 AM #32
BJ, I don't doubt you on the merits of a fast-heat oxy blast, but it's equipment I don't have. Would be handy though ...
As to drilling out the set-screw, I'm with you. However I drilled out to 6mm, the maximum I could go before risk of cresting off the screw threads, and given that the end diameter of the set-screw is (was) tapered, I believe it won't have anything left for interference on the shaft.
Now that the set-screw is drilled out but the pulley is still stuck on, I had tried heating with the little gas torch, but while I'll give it a couple more cycles today, I'm losing hope. Last night I was half-dreaming about how to mount the entire motor on the mill table so I can mill off the pulley.
As to giving the pulley a few whacks further onto the shaft to dislodge the seizure, I have, but rather gingerly because the face of the pulley was marking even with use of a brass drift. But now I'm talking doomsday on the pulley, I might as well give it some much heavier whacks, see what happens.
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22nd Jul 2018, 10:42 AM #33Most Valued Member
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Now you need a press or a puller, pullers are fairly easy to make.
shed
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22nd Jul 2018, 11:35 AM #34
Pullers are here. But I think there is probably a limit to how much you can stress them - Toolex brand from Shonkyen, China, via Gasweld.
But then, if I had some sort of puller that totally enveloped the pulley circumference and was really solidly built with a 32mm diameter acme screw, then it would be a more even competition between shearing the solid steel of the shaft or pulley, stripping the threads off the 32mm acme screw, or actually giving way at the shaft/pulley junction. Nice daydream.
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22nd Jul 2018, 11:46 AM #35Most Valued Member
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I think that you need to post some photis of the problem pulley
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22nd Jul 2018, 12:04 PM #36Most Valued Member
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If you’re at the point of sacrificing the pulley to save the motor shaft, how about cutting it along its axis on opposing sides with an angle grinder? Obviously stopping short of cutting the shaft. If it’s cast iron it should be easy to split it in half with a cold chisel and mallet.
It seems like you’ve tortured your motor enough!
Sent from my iPhone using TapatalkChris
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22nd Jul 2018, 12:27 PM #37Golden Member
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Gunnaduit,
You certainly seem to have a problem with getting this pulley off with the gear you have. As shedhappens suggested a few good photos with dimensions would help. I once had a cast iron pulley on an old compressor that had a very worn bore and someone had used one of the gap filling loctites and it adhered the entire pulley and grub screw on.I drilled the entire grub screw out including all of the threads and into the shaft a little,rotated this hole vertical and filled the hole with a 50/50 mix of acatone and ATF oil and let it sit overnight. I made up a super strong puller out of thick flat bar that fitted right across the back of the pulley not just on the edges and did it up really tight. It did not move to start with it, so I hit the end of the pullers screw with a 7lb lump hammer then re tightened. After several goes it started to give it fought all the way but it came off. I was then able to bore out and bush the pulley and reuse it.
Bob
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22nd Jul 2018, 02:49 PM #38
Photos below. I noticed when I took the motor out into the sunlight to photograph it, that there is an emerald green colour translucent deposit at the bottom of the hole for set-screw that was fitted over the shaft key (see 2nd pic). Could it be some sort of glue? However, still in the sunlight I checked for signs of it in the other setscrew hole (the drilled-out one - see 3rd pic) and at the faces of the pulley where the shaft goes in, but I don't see more. If it was glue, it must have failed in the 'green' hole pictured, because that was the setscrew I managed to remove simply with an allen key.
I gave the pulley a more severe hammering down onto the shaft using a tall circular drift that fitted over the shaft end, so maximising my chances of good even distributed impact with the club hammer (see last pic - btw the bottom of the shaft is supported on a thick hardwood block), but it wouldn't move the slightest.
The bricksaw was made in Australia I think in the early to mid 1990s, seems to have been an expensive one given the generally solid construction - but they did take some shortcuts by spot welding some assemblies together where really bolts would have been a lot classier. Apparently it was owned by a brickie first, then a chippie who I know, but neither even so much as cleaned it let alone had any interest in dismantling any of it as far as I can see. So if the pulley is glued on maybe it was the factory deciding that they 100% weren't going to see any come-backs with dislodged pulleys.
Bricksaw motor general lr.jpgBricksaw motor - green2 lr.jpgBricksaw motor - drillout lr.jpgdrift and hammer lr.jpg
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22nd Jul 2018, 03:32 PM #39Most Valued Member
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OK, I can now see why cutting the pulley off isn’t a simple solution.
Sent from my iPhone using TapatalkChris
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22nd Jul 2018, 03:35 PM #40Most Valued Member
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You'll often find modern day mechanics use loctite on everything and everywhere the old timers were sparingly because stuff like loctite cost money in today's world and often cost a monster back in there prime days so old timers usually use it sparingly, one loctited grub screw is sufficient, these days younger people will loctite both grub screws but its not necessary
with a pulley your likely never going to need to remove it so its likely permanent loctite was used
just heat the grub screw for 5mins with a small propane torch allow it to cool because the grub screw will be steel and may expand faster than the cast iron pulley, after it cools give it a whiz with the impact gun failing that use a mans tool a impact wrench
sounds like that grub screw was built back in the day when our steel was very strong and robust usually grub screws of todays quality are very poor and round out by just looking at them, allen keys i think are harden steel so to snap one of them off that grub screw is 100% loctited
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22nd Jul 2018, 03:47 PM #41
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22nd Jul 2018, 04:35 PM #42
Well I've found the old porcelain cat's bowl is the perfect size for filling with acetone and inverting the motor pulley into. So it can just fully soak in an acetone bath overnight. We'll see what happens in 18 hrs time.
Note the bricksaw's pulley belt cover in the background - 'The Original B Saw' is the brand - whoever that was made by?
Bricksaw acetone bath lr.jpgLast edited by Gunnaduit; 22nd Jul 2018 at 04:47 PM. Reason: added photo
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22nd Jul 2018, 05:18 PM #43Most Valued Member
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You could have saved yourself some drama if you had done this to start with, it would have taken probably 30 seconds to pick the tool up and undo the screw https://www.youtube.com/watch?v=DUOghfo7VGI
If you have not drilled to 8mm and deep enough then the grub screw is likely still holding tight so you will need deal with that.
You will likely need a bearing separator tightened to the bottom of the 2nd belt groove as shown in the pic, then put the puller to work.
If you have not got one then you could make a puller and bolt it to the boss, you would need to drill and tap 2 suitable holes 180 deg apart, one on either side of the shaft, a chunk of plate with the same hole centres and a hole between those 2 for a large nut and bolt.
good luck, shed
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22nd Jul 2018, 05:33 PM #44
You may be right about the hammer-type impact driver being the go-to tool. What I used was an 18V battery-drill type impact driver. I'm not sure which has the more force. The 18V one, torque supposedly rated at 220Nm, wasn't enough that's for sure.
As to set-screw, I drilled it out to 6mm dia, which means that the drill just winged the crests of the threads in the hole. Because the set-screw is tapered off at its tip (I know this from the other one that did come out), and that I drilled about 3mm into the shaft (bit too keen) I can't see how there can be any set-screw left engaging the shaft.
Could I have saved time by soaking in acetone to start with? -- I won't know until the acetone bath has had time to penetrate. At this stage it is still just a theory -- the pulley may have been shrunk on, there might not even be any loctite.
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22nd Jul 2018, 06:27 PM #45Most Valued Member
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Grub screws are generally not torqued down hence we use loctite when someone uses permanent loctite that screw is not going to budge not even 1/10th's of a millimeter it just will not move why u may ask? because that is what loctite is designed to do
the only way to free permanent loctite is to heat the bolt or screw there is no other way around it
wouldn't suprize me if old mate put a tiny dab of loctite on the shaft too some do it especially if your flywheel or pulley is spinning at 3000rpm+
i would most defiantly heat before i drill, if u drill u need to buy drill bits, taps, new screw and a whole s... fighting process when u could have just bought a $25 propane bottle and tip from Bunnings it sure would be a lot less time consuming
actually loctite specially says on there web site to heat the nut,bolt or screw to remove permanent loctited items
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