Welding Tips and Tricks

ok. So I'm having a lot of trouble tuning up a recently purchased used horizontal 4x6 Jet bandsaw. I've searched the forums here. I've read the entire Internet I've joined and searched the Yahoo 4x6bandsaw group. I've watched a LOT of YouTube videos. I've read multiple FAQs etc. I am a friggin' expert.

I am able to get some improvement but not able to get a straight and square cut.

Per instructions I start off testing on a 2x2 piece of wood. By twisting the blade guide assemblies I can eventually get pretty close to square and vertical cuts. When I switch to test on a piece of 1" square tubing 14 gauge the vertical cut is off. It seems to cut straight halfway through and then it dives or veers toward the vise. I can adjust the guides to tilt the blade away from the vise side and it helps with the final veer. However, when I switch from 1" to 1.5" /14 gauge square tubing the vertical cut is curved. As it starts the downward cut it follows the tilt of the blade away from the vise and then about halfway through it curves through vertical and eventually goes back towards the vise... a very very shallow "C" shape. If I adjust the blade tilt to be closer to vertical the final veer gets worse. I just can't seem to get a straight square vertical cut.

What I've done so far:
1. New Starret Blade. 0.020" thick, 14-18 TPI
2. New bearing guides
3. top/bottom wheels are in same plane
4. adjust tracking so that back of blade just kisses the back ridge of the wheels
5. moved the two guide assemblies as close as possible to each other.
6. shimmed to get saw assembly to track vertically on pivot. the bushings are not worn so there's no slop.
7. adjusted blade guide to blade clearance (multiple runs ranging from 0.003" clearance to 0.008")
8. varied blade guide assembly tilt so the blade can be adjusted from vertical to tilted in either direction (undercut and ??cut)
9. varied blade tension
10. varied feed rate by adjusting preload on spring.

Results/Problem
I can't get a straight and square/vertical cut in square tubing. If I adjust the blade to be near vertical, the blade will start to veer towards the vice (undercut) in the lower half of the cut.

As a last resort I cut a bit of 3/16" x 1" bar stock and the C curve is slightly less. Only one test due to time limitations.

Considering the fact that the cut on the thicker material (bar stock) seemed better, I'm considering getting a plain 18 tpi or even a 24 tpi blade to put more teeth in the material.

Does anyone have an idea what to try next?

Apologies for the loooong post and the painfully silly details but I'm getting a bit frustrated. I switched from a portaband to this saw hoping for better easier results and I'm spending days farting around.

I'm going to fix a cocktail and pout.

steve

Sure sounds like you've done your homework- i know that's frustrating. Does Jet have a tech support line you could call?

Have you checked for slop in the pivot point on the saw?

RTFM, I don't know if they do. I suspect this saw is fairly old and been repainted so I'm not sure now much interest they'd have in helping.

Poland308,
The pivot point seems good. I noticed about .050" blade runout from the top of a 6" square to the bottom swinging the saw up and down. I put a shim between the main table casting and the swing arm/spring attachment casting and was able to reduce that runout. I think the blade path is true and repeatable. I've pushed and pulled on it and it comes back to the same point.

Like I said, I may throw another $20 in for a finer pitch blade and see what happens. I bought the saw knowing it had a bad blade. Any testing of the saw before buying would have been pointless as the first advice given is almost always to put in a new blade. I checked for bearing noises, etc. before buying, not overall accuracy.

thanks for responding. it sure is a head scratcher. any other thoughts?
steve

You may want to pull whatever they have in there for a main pivot pin. If the saw was used it may have worn a flat spot on the pin or caused it to taper on one end.

That's a good idea. I'll be out of pocket for a week but will pull the pin once I get back to it.

thanks.

Quick google search:
http://dev.jettools.com/us/en/service-a ... r-support/

Technical Service
1.800.274.6846

8:00am - 5:00pm
(CST Monday-Friday)

I was traveling since my last post and haven't had a chance to try anything until today. I made a few more attempts of changing blade angle and increasing blade tension with no improvement.

I went to Lowe's and bought a Bosch cheapie (not bimetal) 24 TPI blade for $12. I pulled on my days old fancy bimetal Starrett 14-18 TPI blade and replaced it. Changing nothing else, I saw that the cut tracked with the blade angle. As I posted previously, I had the blade angled away from the clamp to minimize the dive at the end, resulting in a "C" shaped cut. with the new blade the cut followed the blade angle! I adjusted the angle to be more square and the cut got more square!!!

I tried other materials and am pretty happy with the end result. not perfect but good enough to get things done.

I have no idea why it worked but I'm pretty happy with the results from the new blade. Just wanted to close this thread with some info.

thanks for the input.

I am completely amazed!

Getting this saw working correctly has saved me a lot of trouble today. I got sooooo many pieces cut (multiples of same size) and the pieces all match. No need to dress them to length or square them up with the sander, grinder, or whatever. Put a bevel on them and weld'em up. Love it.

I thought I'd update the thread as I learned something today.

I am currently doing a project where I'm cutting much thicker material (3x4 x3/8 angle and 3x3x1/2 angle) than what I normally work with (1.5" 16 ga sq tubing). I felt the 24tpi blade currently working well for me was going to be too many teeth for 1/2" material and this was a perfect chance to test my barely used 14-16tpi Starrett blade that was cutting poorly on thinner material.

I swapped blades, made NO adjustments, and it was cutting nearly square. A few tweaks and it's perfect!

I'm thinking that initial problems were because there were too few teeth (14-16tpi) in the thinner tubing wall but it's perfect for thicker.

Extremely happy.

I think you need 2-3 teeth in your material as you cut. Too little and you break teeth, too many and you will be going slow and will put too much material into the teeth.