Stabilized upper guide on 20" bandsaw

[FliesLikeABrick]

Last summer I towed home a Rockwell 28-3x5 20" bandsaw, a ~950 lbs beast with some features that led me to replace my Enco 360 with it:
- 20" capacity whereas the Enco was 14"
- The enco topped out around 150SFPM, whereas the new one can go from ~50 to 4500 FPM
- These have obvious benefits all-around, one of them being that this could allow for occasional resawing of wood for other projects, though I didn't really think about that until after it was home

A number of things on this need some TLC:
- The air blower nozzle is broken off and gone
- The air blower has no belt, it probably broke or was left off during some other change/repair
- The speed control pedal/cable setup was all screwed up, along with the speed indicator needle (now all fixed)
- The upper blade guide had a bearing that would overheat at high speeds
- The upper blade guide.... wobbles? It isn't rigid like you would expect a blade guide to be
- Some issues with the blade tensioning that have since been fixed
- At some point I would like to track down a blade welder for this, it was optional but not installed -- my last bandsaw had a welder and I have a bunch of stock, if someone has a spare welder let me know the dimensions...

This post is about the blade guide wobble issue.

I tore down the upper (movable) blade guide to take the bearing out and see if it needed to be replaced or just cleaned/re-oiled. While I had that out, I realized just now non-rigid the upper guide was.

The clamp to lock the vertical position was doing its job, but what I realized was that the housing that the guide slides in, itself, was moving relative to the frame.

I started to piece this together - something was missing from a threaded hole below the lock handle


The smaller hole in the back seemed to be in the housing for the slide mechanism, because when I wiggled the upper guide arm I could see that piece moving relative to the larger thread.

I could not find good pictures of what was supposed to be here, but figured it should be similar to tracking adjustments I've seen on other saws such as the Enco -- a threaded hub (? not sure the exact name of this kind of part) goes into the big hole, and a smaller bolt passes through that into the thing in the back (for wheel tracking it would be the plate that the spindle mounts onto; in this case it's the outside housing of the guide's slide)

I measured the inner hole to be 3/8-16 UNC, and the outside of the hub would be 3/4 UNF. I do have a 3/4 UNF die in my set of adjustable GTD Little Giant dies, though it was out of adjustment and I didn't have a reference to set it up with; also the set screws in that die were all messed up . After I got that fixed and adjusted, I set to work making this hub out of brass since I had some 3/4 stock sitting around.

First I threaded it with the die, then chucked it up in the Chipmaster

Drilled a 3/16 through hole, knurled where I was going to part it (the bridgeport is out of tram so I didn't want to mill flats or a hex on it right now). Broke some edges, chamfered it....






I picked out a bolt the right length to clamp tight without going through the slide housing and interfering with the slide, threw a copper washer from the junk shelf onto it, a bit of grease on sliding surfaces







And now the upper guide assembly's slide is rock solid and plumb.

Quick and dirty, only ~30 minutes of work after fixing the 3/4 UNF die. The knurls were particularly terrible because I don't have any decent knurling tooling nor practice at it.

This will probably resolve quality/consistency issues we had with resawing a wood project on here, for next time. I don't feel like putting the monster (to us) 1" - 2 TPI blade back on there just to test right now. This lives in the metal shop, and I don't care for the sawdust back there except when we're ready to do a batch of resawing for different projects at the same time

Thanks for reading

 

[benmychree]

I have one the same model, the original adjustment bolt was made of steel and had a 7/8 hex for adjustment with about 3/16 wide head. Mine came from a college machine shop class and was little used, it has the chip blower but no blade welder, it will not stay engaged in high range, and leaks gearbox oil, but it does work, I don't worry about the high range because I bought an earlier 20" Delta from the same school and use it for wood cutting only.

 

[benmychree]

As to the guides, the blade should be adjusted so that the blade does not bear heavily against the bearing, or, yes heating and wear may result.

 

[FliesLikeABrick]

Yep, this does float just in front of the bearing but when resawing hardwood with a 1" blade it does bear pretty hard on the face of it. I couldn't tell if it was lack of recent lube, or just the friction of the blade on the face of the bearing causing the heat. We'll see next time