Kity 613 Bandsaw strip and rebuild (long post)

[scockram]

This is a great thread, I've just discovered it. Thanks @Sideways
I hope no-one minds me hijacking it, rather than starting another new one. It seems like you've already been through the process that I've started, though much more thoroughly.

So I've recently aquired a Kity 613 bandsaw. Very happy with it. (Thanks @Tanglefoot20 ).
Before starting to use it in ernest I'm giving it a clean up and basic stripdown and once over. It looks like it's had an easy life, not many signs of wear and tear, and it's quite heavily built for a small machine; thats reassuring. Couple of things I've found so far though with don't look great.

The first is the motor fan. Mine is an extremely loose fit, so much so in fact that it would just spin on the shaft without the wedge of cardboard that I found jammed in there when I investigated. It's odd because the motor shaft is splinned, as described in Sideways's notes above, but the hole in the plastic fan is just too big. Can't work out if it's been excessively worn at some stage or it's a replacement. Anyway, I can't work out how to fix it securely. It's probably polypropylene or similar so tricky to find a glue that'll hold. Though I wouldn't really want to glue it in place anyway. Has anyone got any good ideas please?

Second thing puzzling me is the polyvee drive belt. It looks to be too close to the inner body panel of the machine. There's also a couple of "tracks" on the pulleys unused, suggesting the belt could be moved outwards or is too narrow. Hopefully this can be seen in my photos. Any opinions on this as well please? I don't think it's actually rubbing, but it's damn close.

Thanks

Simon

 

[clogs]

scockram
looks like the belt has jumped.....BUT once adjusted they never move unless something is loose or been assembled wrong.....
dose it look like the motor has been off...? poss spacer missing...?
a loose motor mount would/could be enough.....
these belts are critical for alignment.....please check for that and if poss with a straight edge....

the fan, u need something like Areldite....never found anywhere to buy fans....bain of my life......
even the manufactures cant/wont supply in a lot of cases.......
it it were mine I'd super glue 3 shims to the motor body and the 3 small pins' nails to get the fan central to the shaft....
obv a dry run untill u get it right then reassemble with the resin....the shims on the moter keeps the fan from wobbling and the pins...enough said...
once the Areldite is cured pull out the pins if u can and remove the rear shims from the motor body.....job done.....

I have a few machines with blown up fans and no replacements....one day I might meet somebody with a 3D printer...lol....

 

[MikeK]

I agree with @clogs and the belt has jumped a couple of rows on the top pulley. Also, a closeup view of the belt at the lower pulley shows a lot of cracking, so you might consider replacing the belt while you have access to it.

 

[Sideways]

Cheers Simon.
It's nice when a thread can get some extra life and remain as a useful reference for people.
Happy to have your photos here. I'll make time and edit it up to put the photos back into their proper sequence.

There are a couple of more recent and far more detailed bandsaw threads that I've contributed to that may be worth a read. One is under my username and is a teardown and rebuild of an Minimax S45, the other is my buddy @deema 's thread on bandsaw blade guides. Taking a machine apart and rebuilding it is a good way to learn about them

 

[scockram]

Thanks for the advice guys. I've not been able to spend much time on this at all over the last week or so. Work and other stuff, life in general has got in the way!

scockram
looks like the belt has jumped.....BUT once adjusted they never move unless something is loose or been assembled wrong.....
dose it look like the motor has been off...? poss spacer missing...?
a loose motor mount would/could be enough.....
these belts are critical for alignment.....please check for that and if poss with a straight edge....

the fan, u need something like Areldite....never found anywhere to buy fans....bain of my life......
even the manufactures cant/wont supply in a lot of cases.......
it it were mine I'd super glue 3 shims to the motor body and the 3 small pins' nails to get the fan central to the shaft....
obv a dry run untill u get it right then reassemble with the resin....the shims on the moter keeps the fan from wobbling and the pins...enough said...
once the Areldite is cured pull out the pins if u can and remove the rear shims from the motor body.....job done.....

I have a few machines with blown up fans and no replacements....one day I might meet somebody with a 3D printer...lol....

So I jumped the belt back into the correct grooves easily enough. Bit surprised about that but the tension is ok I think, it's pretty tight. I've had a good look at everything and can't see anything amiss, that's caused it to jump in the first place. Doesn't look like the motor has been disturbed any time recently. I will do a proper alignment check as soon as I get time though, with blocks and a straight edge. I've ordered a new belt anyway, so will fit that in due course. Might discover the cause of the problem in the process of doing that.
The motor fan is a tougher nut to crack. I like your thinking with the shims and pins @clogs . Not applicable in this case though as the back of the fan extends over and encloses the motor. But, it's not really needed anyway as the hole is tight enough to fit centrally on the shaft already, just not tight enough to stay on. I could just araldite it on as it is, but reluctant to do that in case I need to take the fan off in future to do any work on the motor.

I agree with @clogs and the belt has jumped a couple of rows on the top pulley. Also, a closeup view of the belt at the lower pulley shows a lot of cracking, so you might consider replacing the belt while you have access to it.

View attachment 147091

Good spot there, thanks for that. I'd not actually noticed the cracking. My camera is better than my eyes! Really going have to give in and start wearing my glasses in the workshop.

Fan on and over back of motor.

 

[Ttrees]

Does the fan not rotate up to speed, CA superglue or possibly epoxy and some dense plastic possibly Bakelite shavings might make a suitable putty.
Failing that would it be possible to plug and redrill ?

 

[scockram]

Does the fan not rotate up to speed, CA superglue or possibly epoxy and some dense plastic possibly Bakelite shavings might make a suitable putty.
Failing that would it be possible to plug and redrill ?

No, it just slips off the end of the shaft when it gets up to speed. The hole in the fan is slightly tapered and there's no axial restraint. If there was I think it would stay tight enough and be fine. Thought about tapping a hole in the end of the shaft but I can't imagine that'd be easy as it won't just be mild steel. Had a flash of inspiration last night in bed; I'm going to epoxy a washer on the end instead. Hopefully that'll do it, and shouldn't be too hard to remove should I ever need to.

 

[Ttrees]

I wonder if a piece of copper pipe might be another method.

Failing all repairs, or replacements which I'd imagine would be available should it be a standard shaft,
its likely someone is out there who makes stuff like this with a printer.
Have a look at this thread for instance.

Good luck
https://www.ukworkshop.co.uk/threads/sip-01446-12-table-saw-details-repairs-and-review.125956/

 

[scockram]

So the fan is successfully secured in place now, I'm happy with the result. It turned out to be quite simple in the end. I cut a disc of aluminium sheet rather than using a washer.

I'm now a bit stumped about changing the drive belt. I feel stupid asking this, but how does one go about changing the belt? Do I take the wheel off the shaft, or take the wheel plus shaft out of the housing?

 

[Sideways]

Looking at the big lower wheel, you see the two bolt heads below and right of the small pulley ? Those are adjustable motor mounts. You loosen them, and maybe a third one above the small pulley, in a round hole not a slot, to allow the small pulley to be pushed closer to the right. The belt will then come off the drive pulley.
Then remove the big lower wheel so that you can change the belt. That probably means releasing two of the four bolts with locknuts at the back of the machine until you can pull the wheel and spindle forwards and out. Leave one vertical and one horizontal bolt where they are if possible, slackening off two.
When you come to put the spindle back with a new belt already around the big pulley, the two bolts you left alone will hopefully retain the alignment / tracking so you won't have to do that entirely from scratch.

Thread the belt around the two pulleys and lever on the side of the motor to tension it, then nip up the bolts in the elongated slots.

I don't think that removing the circlip in the middle of big wheel helps. That just holds the front bearing in place. I think there is a second bearing behind that and you won't be able to pull the wheel off the spindle from the front.

If your bearings are old by the way, consider changing them while you are doing this. Bearings are cheap and the 613 uses standard sizes that are easy to buy online.

When all is done, check with a long straightedge that the two band wheels are lined up. One should not be in front or behind the other and they shouldn't be at an angle either side to side or top to bottom. "Coplanar" is the word
This is part of adjusting tracking of the bandsaw to get the blade running in the correct position on both tyres.

 

[scockram]

Looking at the big lower wheel, you see the two bolt heads below and right of the small pulley ? Those are adjustable motor mounts. You loosen them, and maybe a third one above the small pulley, in a round hole not a slot, to allow the small pulley to be pushed closer to the right. The belt will then come off the drive pulley.
Then remove the big lower wheel so that you can change the belt. That probably means releasing two of the four bolts with locknuts at the back of the machine until you can pull the wheel and spindle forwards and out. Leave one vertical and one horizontal bolt where they are if possible, slackening off two.
When you come to put the spindle back with a new belt already around the big pulley, the two bolts you left alone will hopefully retain the alignment / tracking so you won't have to do that entirely from scratch.

Thread the belt around the two pulleys and lever on the side of the motor to tension it, then nip up the bolts in the elongated slots.

I don't think that removing the circlip in the middle of big wheel helps. That just holds the front bearing in place. I think there is a second bearing behind that and you won't be able to pull the wheel off the spindle from the front.

If your bearings are old by the way, consider changing them while you are doing this. Bearings are cheap and the 613 uses standard sizes that are easy to buy online.

When all is done, check with a long straightedge that the two band wheels are lined up. One should not be in front or behind the other and they shouldn't be at an angle either side to side or top to bottom. "Coplanar" is the word
This is part of adjusting tracking of the bandsaw to get the blade running in the correct position on both tyres.

Thanks Sideways, for the comprehensive answer, great. Ive finally got a bit of time to myself so I'll do this belt now. Ive investigated the old one more closely, its knackered so definitely due replacement.
Both wheel bearings are silky smooth and quiet with no play so theyre fine for now.

I get what you mean about the two adjustment bolts being left in place, good tip. I work in automotive design and manufacture so spend a lot of time thinking in 3D geometry!

 

[Sideways]

Excellent
I am in awe of people who have great 3D spatial awareness.
Acrobats, freestyle skiers, fighter pilots ...5 axis CNC programmers and woodcarvers !

 

[scockram]

Freestyle skiiers are on another level entirely. The stuff they do is just incredible, the way they rotate around multiple axes like that. They must operate in 4D to be able to successfully land some of those tricks!