Cut Out Results - Cylinder vs Cone

[Jim Erickson]

I've been doing some practice cuts on my Hawk, and I need to know if my results are typical, or whether there is something about my technique that is producing this result.

In prep for my first project, which is a box, I have been cutting out small circles in some 1 3/4" pine.  The cut outs end up being cones rather than cylinders.  The first cut out caused me to check the table/blade setting, and I discovered a small discrepancy in the adjustment, which I corrected.  The second was less cone shaped, but still larger on the top than the bottom.  Similarly, the third is also cone shaped.  Is this to be expected, or is there something I'm doing wrong?  I'm cutting at 5.5 on the speed control, using a #9RG-9/6 TPI PGT DBL tooth blade.  BTW, I don't completely understand the blade designation.  They are blades that came with the saw, and are the previous owners labeling.

Any helpful comments are appreciated.  Thanks.  Jim  PS:  the circles are about 1.25" in diameter.

[trackman]

Make sure your table is 90 degrees to the blade.  That thick of wood I would say you are putting pressure on the side of the blade. Take it slow and  Let the blade do the work  

 

[Roberta Moreton]

It also has to do with how much pressure you’re putting on the blade. I have had trouble with 3/4” thick puzzles because of this. Too much pressure resulting in puzzles that only go together from one side because of a tapered cut. Boxes are even harder because they are thicker. I have accomplished a few boxes, but they are not my favorite to do. 

[Roberta Moreton]

Just now, Roberta Moreton said:

It also has to do with how much pressure you’re putting on the blade. I have had trouble with 3/4” thick puzzles because of this. Too much pressure resulting in puzzles that only go together from one side because of a tapered cut. Boxes are even harder because they are thicker. I have accomplished a few boxes, but they are not my favorite to do. 

 

[dgman]

1 1/4” is extremely thick to cut on a scroll saw but is doable. If, as you say the table is perfectly square to the blade, you are applying lateral pressure to the blade causing it to bow when you are turning the wood. It takes practice to cut without the bow. Make sure you have plenty of tension on the blade. It must make a high “ping” when you pluck the blade. Practice using thinner wood and a larger diameter circle. Once you have mastered that, then move up to thicker wood. Good luck!

Edited May 19, 2021 by dgman

[fredfret]

Front to back of the blade should be square to the table as well as side to side. 

[Jim Erickson]

Thanks Fred.  I do have the saw set for aggressive cutting, so I don't think the back of the blade is square to the table.

Thank you all for the advise.  I'll check the tension of the blade, and practice moving the material more carefully.  Jim

[ben2008]

I use PGT blades all the time and have used them for many years. PGT "Precision Ground Tooth" are Olson blades. They cut straight and they last a long time, however, they are aggresive. The key is to not push to either side of the blade. As others have said, let the blade do the work. I find if I slow the saw down and push slowley and keep the blade 90 degress to the table you will not have a problem. Yes, it takes longer. However, I don't do this to mke money. I do it for fun.  Perfect circles are not easy to make.This takes practice. Sometimes a lot of practice.

Here's a link to the Olson web site. You can get all the information and what the various designations about the blades there.

https://www.olsonsaw.net/shop/scroll-saw-blades/plain-end-scroll-saw-blades-5-in-6-in/skip-reverse-tooth-pgt-precision-ground-tooth-5-in/

Good luck.

Edited May 19, 2021 by ben2008

[Rockytime]

2 hours ago, fredfret said:

Front to back of the blade should be square to the table as well as side to side. 

I realize the Hawk has an adjustment for aggressive cutting. Mine did. The question has come up in the past about front to back 90 degrees. Cant remember it but I think it was about the Hegner which I now have. My blade is ever so slightly off 90 degrees. There is no adjustment that i am aware of to correct that. I don't mean as if that were a flaw but as the normal arcing of the blade. Years ago a Hegner salesman told me that the Hegner is the only scroll saw in which the blade is perfectly straight all the time. I have now found that not to be true. Don't know if there are other machines that do. My bad! I just hijacked this thread so there is no need to reply. I'm probably talking through my hat!

[OCtoolguy]

That old problem of the blade not being square in the clamps has been talked about before. The blade must be in alignment top to bottom before adjusting to square the blade to the table. 

Edited May 19, 2021 by octoolguy

[Jim Erickson]

My blade, even in the less aggressive position, is not vertical.  It tilts slightly forward, at the top and of course moves up and down in a slight arch.  I think that arch is smaller in the Hawk and Hegner machines than most others because of the design of the machines.  My guess is that somewhere during the up/down stroke the blade is actually perfectly vertical.  Haven't bothered to move the arm up and down and measure to see.  Jim

[OCtoolguy]

Jim, have you checked to make sure the blade is in the same plane in both clamps? It's important that the blade sits perfectly vertical. Hard to explain but if you have blade clamps that have a clamp screw and an anvil screw then there is an adjustment that has to me made so that the blade sits vertical. Once that's done, then you can adjust your table so that it is square to the blade. Only then will any of the above suggestions matter.

[Jim Erickson]

Thanks Ray.  I just checked, and sure enough the top clamp was not centered.  I adjusted it,  The anvil screw must have course threads because turning it just a little centered the blade.  Bottom clamp looked centered.  After that I checked the side to side plumb, and had to reset the table.  Thanks for pointing this out.  I probably never would have figured that out, and just written off any resulting cut error as simply operator error.  Jim

[OCtoolguy]

1 minute ago, Jim Erickson said:

Thanks Ray.  I just checked, and sure enough the top clamp was not centered.  I adjusted it,  The anvil screw must have course threads because turning it just a little centered the blade.  Bottom clamp looked centered.  After that I checked the side to side plumb, and had to reset the table.  Thanks for pointing this out.  I probably never would have figured that out, and just written off any resulting cut error as simply operator error.  Jim

Glad it helped. I had the same problem and someone here on The Village set me straight.

[ben2008]

14 hours ago, octoolguy said:

Glad it helped. I had the same problem and someone here on The Village set me straight.

 

14 hours ago, Jim Erickson said:

Thanks Ray.  I just checked, and sure enough the top clamp was not centered.  I adjusted it,  The anvil screw must have course threads because turning it just a little centered the blade.  Bottom clamp looked centered.  After that I checked the side to side plumb, and had to reset the table.  Thanks for pointing this out.  I probably never would have figured that out, and just written off any resulting cut error as simply operator error.  Jim

This is the place to come for help when it comes to scroll saws. There are many knowledgeable folks here.

[kmmcrafts]

Using a Hawk Ultra saw you'll likely never get a perfect cut in that thick of wood with the blade in the aggressive cut position.. I've never been able to get nice clean cuts on the aggressive setting. But works very well in the front position. There needs to be a in between position, well the newer saw is variable so you can tune it for the best possible cut for said material.. Look for a G4 or BM series saw for that must have upgrade if you're doing a lot of thick wood cutting.