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I recently took a machine shop class at a local school.
Here are some of the projects we made in class:
The rec.crafts.metalworking FAQ has lots of good information:
The 4x6 Horizontal/Vertical Bandsaw FAQ is required reading if you own one of these puppies:
The rec.crafts.metalworking newsgroup is very good reading:
So, after about a year of moderate use, I found my once very accurate Harbor Freight 4x6 bandsaw was now cutting at an angle. It used to be able to slice a piece of 2" flat stock across the face and be within about .025" top to bottom. Now I'm lucky to be within 1/8" and often its worse.
I tried all the usual suspects, new blade didn't help, adjusting the blade tracking and guide rollers didn't help. Initially, I found if I stuck a shim under one of the legs, I could sort of get a straigter cut, but it wasn't a set angle it was off. Its hard to see in the pictures above, but I tried to get a shot of the blade coming down and up to about an inch off the table, it was nice and straight, then the last inch, it would pull away from the square edge and end up about 1/8" away, almost like it was cutting on a large radius.
So, after lots of snooping around, I found the cause of the problem. The whole upper saw frame seemed to be twisting as it came down. I first though the pivot rod had bent, so I tried to twist it 1/4 turn and see if it got better, no luck. Then I noticed the back pivot hole had become elongated due to the contant pressure of the counter weight spring. The soft cast iron of the base had worn away, letting the spring pull the back of the frame forward as it came down (the force on the spring is the most when the saw is fully down). I released the spring tension and could feel the play in the saw frame when it was down. When it was up or when the spring was under tension, there was no play apparent, only with no load could I feel it. So, out came the Sawzall and off came the cast iron ears.
Next, I added and extension bracket made from 1x1x1/8" steel angle, to which I intended to mount some split pillow bushings (pictured above). However, I later found that it is not possible to use a bushing on the near pivot, due to the tight fit with the saw drive wheel. But, all was not lost, I simply welded the cut-off cast iron tab to a pice of 1x3/16" flat bar (no special welding rod was used), then shimmed that up to match the center line of the rear bushing (the one that takes all the load) and bolted it to the frame. Now, not only is the saw pivot fully adjustable, but the rear bushing is greaseable and easily replaceable if needed.
Anyway, if anyone is interested in doing this fix, I just happen to have a spare split bushing, that I ordered but did not use, that I set up with a grease fitting, that I would part with for $30 (shipping included) the bushing is $28.50 itself, from McMaster-Carr. While I chose to weld some parts, this whole fix could be done with tapped holes and bolts. Now, I have full adjustability over the saw pivot, each side can move forward and back, side to side, and the near side may be shimmed up and down to perfectly align the plane of the blade cut with the table and fence. That above pretty much covers the fix, if there is something you are not clear on, let me know.
So, now that I had my saw cutting straight again, I quickly ran into an old problem. I periodically have to cut things at greater than 45 degree angles, beyond the range of the built in fence. In my case, I need to cut 2-1/2" square tubing at a 55 degree angle (and no, it won't work to cut it at 35 and turn it around, BTDT). So fine, I slip a 10 degree wedge in betweenm the fence and the stock, but the clamp is too close to fit. So, I remove the clamp try to hold down the stock with a c-clamp. This works, but the clamp prevents the saw from coming down all the way and I have to reset it to clamp over the blade after half the cut is done, royal PITA.
So, one day at Harbor Freight, I see this clamp that looks like 1/2 of a pair of Vice Grips, with a screw stud where the other half should be. Its labelled as a welding hold down clamp or something like that. I simply drilled a 1/2" hole for the stud in the saw base, screwed it down tight and it works great to hold odd-sized stock in place and is low enough to fit under the saw frame. It also fits just fine in the stock holes and slots, too. I only needed to drill the hole for my odd-angle cut piece, as pictured above.
[Last updated: 27.February.2005]