Jigsaw blade deflection

[Chuck Ketcham]

I've been practicing cutting a curve into 3/4" red oak with my Bosch jigsaw. No matter which jigsaw blade I use, I seem to be getting some blade deflection causing the vertical axis to not be plumb. So, I'm either faced with cleaning up the cut, or cutting it with a different method. Any suggestions on how to proceed? I don't have a bandsaw right now, but perhaps I will buy one. However, the piece of wood is 60" x 12" and it might be rather unwieldly cutting on a bandsaw. Comments appreciated.

Chuck

[Dave Falkenstein]

Do you have the newer model Bosch saw with blade guides? Blade guides make a huge difference in the squareness of the cuts.

Another thing to try is a different blade. Try using a blade that is specifically designed to make square cuts. I'm not sure what choices you have with Bosch blades, but Festool blades are interchangeable. Festool makes several blades that might help. For example, the Festool S 75/4 FS and S 75/4 FSG blades are specifically designed for square cuts. More information on Festool blades here:

http://www.bobmarinosbesttools.com/docs/JigsawBladeCompChart.pdf

[Chuck Ketcham]

I have the Bosch model 1587AVS, with the blade roller guide. I used a Bosch T101A0 blade. The Festool equivalent blade is the S50/1.4 K. Perhaps the problem is my technique?

[Bruce Benjamin]

I have the Bosch model 1587AVS, with the blade roller guide. I used a Bosch T101A0 blade. The Festool equivalent blade is the S50/1.4 K. Perhaps the problem is my technique?

The model of jigsaw is your problem. The later models, (1590 or 1591) have a different type of blade guide that more or less grips both sides of the blade. I have the 1591 and it works great.

Bruce

[Jim Becker]

You might try slowing your cutting rate substantially to take most of the stress off the blade.

[glenn bradley]

Another happy 1590 owner but that may or may not be the problem. How tight are the curves on the design? Could this possibly be done with the jigsaw for "rough" cutout and then cleaned up with a router and a pattern bit? Your shapes may be too tight for this solution but thought I'd throw it out there.

P.s. Jim makes a good point. I run my saw very slowly for detail work. The constant torque makes this very do-able even in thick oak.

[Dave Falkenstein]

I have the Bosch model 1587AVS, with the blade roller guide. I used a Bosch T101A0 blade. The Festool equivalent blade is the S50/1.4 K. Perhaps the problem is my technique?

If I have the model numbers straight, your saw in an older model that did not incorporate blade guides. The newer saw is a model 1590EVSK. All of the decent jig saws have a roller guide. The new model Bosch and the Festool saws have blade guides to keep the blade from deflecting.

I think another problem is your choice of blade. The blade you are using is rather thin (front to back), and more easily deflected than wider blades. Here's what Festool's blade chart says about the S50/1.4K:

"Curve cutting in plywood, plastics, laminated particleboard, hard and soft wood 5/64”-3/4”. Work without orbiting action."

I think you will get better results with the Festool S75/4FS or S75/4FSG blades, or the Bosch equivalent of those blades. The S75/4FSG is especially good for precise angles (i.e. square cuts) and cutting curves. (The FSG blades are unique to Festool and do not have a Bosch equivalent.)

BTW - I had the same type of Bosch jig saw you have, without blade guides, but mine was the barrel grip model. I got tired of the poor quality of cuts in thick material - it was hard to get square cuts. I gave my Bosch saw to my son-in-law and bought a Festool, and never complained about the quality of the cuts again. Since Bosch added blade guides to their saws, it is my understanding that the cut quality is much improved.

[Danny Thompson]

Think of it like a dogsled. If you pushed it, it would tip. Instead, let the saw do the cutting. Guide instead of push.

Good luck.

[Bruce Benjamin]

Think of it like a dogsled. If you pushed it, it would tip. Instead, let the saw do the cutting. Guide instead of push.

Good luck.

While I understand the point you're trying to make, if you don't push the saw it won't move. You need to push gently and concentrate on pushing in the direction of the cut around a corner. I've found that my 1591 barrel grip cuts beautifully around corners and I believe that at least part of the success is due to gripping the saw lower to the surface and also due to the saw blade guide that the 1587 doesn't have.

Oh, and for the record, I lived about 70 miles north of Nome, Alaska for a year and saw plenty of dog sleds getting pushed over the jumbled up ice. They didn't tip over. ;):D But they also weren't very good at cutting wood.:D

Bruce

[Lee Schierer]

The blade makes all the difference when cutting curves. It also depends on the radius of the cut you are trying to make.

You can cut circles with a router and circle cutting attachment (make your own circle jig from 1/4" lexan or plywood.) Rough cutting the curve with the wayward jig saw will remove most of the material and then clean it up with a router. This won't work if the curve is not a part of a circle.

[Tom Veatch]

... You need to push gently and concentrate on pushing in the direction of the cut around a corner...

This echos my experience with curve cutting with jig/sabre saws. Be very, very careful to push parallel to the cut and avoid any side load on the saw. I've found that a side load to the left causes the blade the deflect such that the cut tapers with the bottom of the cut to the right of the top and vice versa.

If I take it slow, apply constant, light pressure parallel to the cut line, avoid side loading, and let the saw cut at it's own pace, I find that even my 25 + year old Craftsman does a pretty fair job of cutting square to the surface. But if I try to push the saw in the direction of the curve (side loading the saw toward the inside of the curve - a natural tendency) then the bottom of the cut flares toward the outside of the curve.