Shopsmith Forums

I am POSITIVE this is user error... However.... This is what is happening.

I have the SS Mark 7. Have had it for a while but haven't had the time to use it like I had hoped. So I'm still learning.

With that said here is the issue I'm experiencing.

When I cut short stock. Say 20 to 30 inches it appears to be cutting the stock in an arc. So when I rip down a board and assemble them to glue there is either a gap in the middle or a gap at one end. Like a solid 1/8" kind of gap. I have the saw guard on and it passes through fine. Until I put them together edge to edge. AND I have joined one side so it starts out square. The wood has been indoors for a couple years so I know it's good and dry and not getting any movement there.

It has to be how I'm feeding it into the saw or something.

Has anyone else ever experienced this? If what what do you do to correct it?

Thanks in advance guys.

Kevin

What you describe (or at least how I envision it) just cannot happen without some kick back.

Make certain that all five locks are secure (especially the headstock lock and the fence lock and the carriage lock.

Set the fence so that the distance from the blade to the fence equals the width of a straight board that you have. With power off pass that board between the fence and blade as though you were ripping it. Does the board pass through without interference.

Now rip a board and see if the problem still exists.

Check alignment of riving knife portion of upper guard to blade.(?) Ideally there is no contact, the riving knife is in the kerf with no contact on either side. There's an adjustment for this, presumably in the manual.

- David

I agree with your theory Dusty. All locks were checked and verified before I ever turned on the saw. Always do... Part of my start routine. The Riving knife is aligned properly as well. I loosely tried what you suggested and I was able to finesse it through without any trouble. I thought maybe it was a small table and fence kind of thing. Like it will not cut properly if I'm not feeding it spot on. I'm thinking of building a jig for the fence to lengthen the feed side of things.

I agree with Dusty. I don't see how thus can happen (particular with a 1/8" gap) with out a kick back. Maybe at one end of the stock if something moved but not a curve in the middle of the stock.

Being inside for a couple of years does not mean that the wood will not move when cut. Is this happening with everything you cut? Have you tried some different stock (species, thickness, etc.) to see if the same thing is happening.

Don’t rule out anything initially. For example, don’t assume that your fence is straight until you have independently verified that it is.

I once had a virtually identical problem with a track saw. After triple-checking every possible alignment issue, a Google search turned up a guy who had had the same problem. He replaced his blade, and the problem disappeared. So I replaced my stock Makita blade with a new Festool blade, and that eliminated about 90% of the curvature in the cut line. But I was shooting for near perfection for whatever the application was, so I then invested north of $100 in a Forrest blade with a slightly thicker plate. That one cut dead straight, within my measurement capabilities, and it still does.

I never did nail down the precise root cause, but there were apparently some weird blade dynamics at play, which I suspect were a result of the cheaper blades being inexpertly “tensioned”. I gather that is still a manual process, with results that reflect the skill of the tensioner.

That may or may not be your issue, but I’d sure be interested to learn if a different blade works better for you.

Well guys I can honestly say I definitely did not get a kick back but I cannot definitely say the wood did not move on me. It has in the past... I have had it close the saw kerf and pinch my riving knife and all sorts of issues in the past cutting this batch of walnut. So I can't rule it out but... I ripped a 5.25" by 34" board at 2.5". That first piece is straight as an arrow. The second piece I ripped had the arc to it. Why would one move and not the other? I had 3 boards that were 34" and all three of them did the same thing on the second cut. I could try cutting some other kind of wood to see if I have the same issue. That would be easy enough. If I can get the rain to let off long enough to the get saw out today I'll give that a try.

Here is what I have. Thought maybe some pix might help.

If I am reading this correctly, you are ripping 34" long boards (a 5.25" by 34" board at 2.5") and the first came through straight as an arrow but the second has the "arc" to it. Even though they had been jointed is it possible the second board did not have a totally straight jointed edge?

EDIT

Since you posted the pictures while I was finishing my post, in the first picture the boards 1 thru 4 look good but there is a gap between 4 and 5 and a smaller gap between 5 and 6 at the far end. Is the width of the boards the same all the way along the length?

I guess you could try cutting a piece of plywood to see if it's the saw and not the wood.