Keeping trunnions adjusted on Craftsman TS

[Chris S]

I had some spare time to try to mess with the saw recently and I can't figure out what's wrong with it. With the blade raised all of the way, I can get it aligned with the slot, and it stays that way. The problem is, that when I lower the blade to cut dadoes or rabbets, the rear of the blade gets farther away from the slot.Or, I guess the front could be moving closer. Whatever it is, it won't keep it's alignment. When I raise it back up fully, the alignment is dead on. What the heck is going on?

[toolguy1000]

on first blush, it sounds like the arbor housing is bent or twisted. the arbor housing is supposed to rise and fall in a perfectly vertical plane. it does this by rotating in the trunion cradle as the helical threads on the end of the lift screw engage the teeth on the underside of the arbor housing. conceivably, if the arbor housing is twisted, once aligned to the miter slots at the point of maximum blade height it will "move " relative to the miter slots as the twisted portion assumes differing positions as the arbor housing rotates in the arbor cradle moving the blade up and down.

have all the bolts under the table top been torqued? while there isn't a lot of linkage under the top, something loose could cause unwanted movement. when the trunion bolts were tightened, were all 6 bolts torqued, and torqued in a kind of alternating pattern so as not to skew the trunions prior to maximium tightening.

can someone raise and lower the blade while you observe the trunions, arbor housing and trunuon cradle? also, have the arbor and arbor flange been checked for runout?

and just for the record, it sounds like the blade is being kept at max height for all thru cuts ("With the blade raised all of the way, I can get it aligned with the slot, and it stays that way. The problem is, that when I lower the blade to cut dadoes or rabbets, the rear of the blade gets farther away from the slot".). if the blade is only being lowered for non-thru cuts, that can be quite dangerous. it also contributes to blade heat build up and consequently shortened blade life. blades are, according to freud blades, to be employed so that the bottom of the gullets are at or just below the surface of the workpiece. this allows the teeth to shear their way thru the material rather than chop down on it.

keep us posted on developments here and good luck in resolving this issue.

[Chris S]

on first blush, it sounds like the arbor housing is bent or twisted. the arbor housing is supposed to rise and fall in a perfectly vertical plane. it does this by rotating in the trunion cradle as the helical threads on the end of the lift screw engage the teeth on the underside of the arbor housing. conceivably, if the arbor housing is twisted, once aligned to the miter slots at the point of maximum blade height it will "move " relative to the miter slots as the twisted portion assumes differing positions as the arbor housing rotates in the arbor cradle moving the blade up and down.

have all the bolts under the table top been torqued? while there isn't a lot of linkage under the top, something loose could cause unwanted movement. when the trunion bolts were tightened, were all 6 bolts torqued, and torqued in a kind of alternating pattern so as not to skew the trunions prior to maximium tightening.

can someone raise and lower the blade while you observe the trunions, arbor housing and trunuon cradle? also, have the arbor and arbor flange been checked for runout?

and just for the record, it sounds like the blade is being kept at max height for all thru cuts ("With the blade raised all of the way, I can get it aligned with the slot, and it stays that way. The problem is, that when I lower the blade to cut dadoes or rabbets, the rear of the blade gets farther away from the slot".). if the blade is only being lowered for non-thru cuts, that can be quite dangerous. it also contributes to blade heat build up and consequently shortened blade life. blades are, according to freud blades, to be employed so that the bottom of the gullets are at or just below the surface of the workpiece. this allows the teeth to shear their way thru the material rather than chop down on it.

keep us posted on developments here and good luck in resolving this issue.

Toolguy,

Thanks again for all the replies.

No, I am not keeping the blade all the way up. With saying "it stays that way", I was referring to the blade staying aligned with the slot. As far as tightening the trunnion bolts, I was very careful while doing this and I took several measurements during the process. I first tightened the middle bolts on the front and back trunnions, and then alternated among the corner bolts. Tomorrow I will check for twisting when the blade is lowered.

I guess if all else fails, I'll keep in mind that this was simply a $50 investment, and I could probably make my money back by selling the motor. Through reading your posts, I will at least be armed with more info on how to determine if my next Craiglist find is really a gem or not.

[eezlock]

keeping trunnions aligned on tablesaw

Chris, first off, I'm no expert here, so take this advice for what it is worth.
I didn't see in your post about the saw, if you checked the saw arbor with the belt on vs off the saw. A used saw of that age and condition has probably had
the same motor pulley, arbor pulley and belt since it was new and never been changed. That being said, if you can find two matching sized machined pulleys
not stamped or cast one's and a link belt install them, align them straight in line with each other....most likely this will cure your blade alignment headaches!

Machined pulleys will make a world of difference in how that saw runs, sounds,
aligns and how well it stays in adjustment for a looooong time! It is worth the
little extra expense! Give it a try, and let us hear about how it did.eezlock

[Chris S]

Chris, first off, I'm no expert here, so take this advice for what it is worth.
I didn't see in your post about the saw, if you checked the saw arbor with the belt on vs off the saw. A used saw of that age and condition has probably had
the same motor pulley, arbor pulley and belt since it was new and never been changed. That being said, if you can find two matching sized machined pulleys
not stamped or cast one's and a link belt install them, align them straight in line with each other....most likely this will cure your blade alignment headaches!

Machined pulleys will make a world of difference in how that saw runs, sounds,
aligns and how well it stays in adjustment for a looooong time! It is worth the
little extra expense! Give it a try, and let us hear about how it did.eezlock

Thanks for the advise. A link belt and pulleys are on my list to do. I know that at least one of my pulleys is out of round, so my expectations for accuracy have been a bit tempered. I have not tried belt on v/s belt off to see if that makes a difference.

My main concern with originating this post, was that I felt like the trunnions weren't staying in place. When I did make the big adjustment on the front and back, they seem to be staying in place now. I guess over time, the front one got too far to one side, and it was causing the rear to "bottom out" if you will, in the adjustment holes. Now there is a little free area on both sides of the bolts, and it seems to be rock solid as far as movement.

[toolguy1000]

Ok, so I got a dial indicator from HF this morning and did some testing. I tilted the arbor to 45 degrees and screwed the dial indicator to a piece of scrap that I had cut at 45 degrees. I then clamped the wood to my miter gauge. As I rotated the arbor, I was getting no more that .02" movement on the dial indicator. I think this is a good thing!?! The arbor feels very firm, has no wobble, and rotates easily.

hopefully, you mean .002" .02" would be unacceptable.

I then put a blade back on, and tested to see how it lines up with my miter slot. I was getting about .03" movement as I slid the dial indicator across the face of the blade. Is this acceptable? I tried another blade, and got different numbers.

pick one blade and one tooth on that blade. sliding the gauge across the blade doesn't measure the arbor. try this procedure:

http://www.newwoodworker.com/algntruns.html


I'm thinking now that I really need to invest in some good blades. I was using a few cheap Irwin blades. Please tell me if I'm off track here. Thanks for your help again.

the best WWII blade on adefective arbor will cut like a cheap blade. make sure the guts of the saw (arbor flange, arbor stem, etc) are sound before spending a lot on a blade that may not address your issue.

Also, my pulleys and belt are complete junk. I can tell by looking at the pulleys that they are out of round. Oddly, the saw actually doesn't vibrate too much with junk pulleys. I'm guessing that replacing them and getting a new belt would help me even more.

correct. machined pulleys and a link belt will greatly reduce transmitted vibration. in the meantime, check that the motor and arbor pulleys are coplanar. check your owners manual for that adjustment.

hope this helps

[BrazosJake]

Google inline industries for machined pulleys. They also make the pals.