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New type of scroll saw control any good?

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Forum topic by NewSaw posted 03-08-2017 09:41 PM 1555 views 0 times favorited 11 replies Add to Favorites Watch
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NewSaw

5 posts in 279 days


03-08-2017 09:41 PM

Topic tags/keywords: scroll saw

Hi. I work for a small (OK, tiny) company that has recently modified a scroll saw with a new drive scheme. The saw starts slow, say one up/down cycle per second, then, as you push your piece in, it speeds up to the level that you are pushing. So, if you have a thin piece and push lightly, it might only get to 150 RPM. I’ve pushed 2×4s in and it can zip right up to full speed and carve a quick cut.

I’ve not done a lot of cutting, but it seems to be helpful. If you back out of a cut, it slows considerably, though the natural friction and binding tend to keep a decent speed up, which seems fine.

Our thought is that the speed is appropriate for how much you want to cut, and the slow speed is very nice; it’s quiet in between cuts, and allows you to position your piece before cutting, then you dictate the cut rate as you push and turn the piece. We have adjustments for top speed and attack aggressiveness (how fast it speeds up for how much load). It even seems interesting and fun to use compared to a steady speed (which we have available and adjustable with a knob). We might add an adjustable minimum speed.

You can mimic this behavior with a foot pedal, but it requires you to control both hands and foot position.

Would this be a helpful product? We have similar ideas for other wood working tools in the mix and just recently tried the algorithm on the scroll saw.

Thanks, Bill.


11 replies so far

View MrUnix's profile (online now)

MrUnix

5985 posts in 2033 days


#1 posted 03-08-2017 10:18 PM

I wouldn’t find it useful at all… in fact, it would probably be more aggravating than anything else. I’m sure others will have differing opinions. YMMV.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View TheDane's profile

TheDane

5328 posts in 3498 days


#2 posted 03-08-2017 10:23 PM

I would not buy it … I want to be able to vary speed according to the material I am cutting. IMHO, it would be a solution in search of a problem.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View William Shelley's profile

William Shelley

477 posts in 1304 days


#3 posted 03-08-2017 10:46 PM

It’s an interesting idea but I feel like the cut quality would suffer.

The opposite relationship however is quite useful. Variable Frequency Drives can do this, when connected in a feedback loop with a shaft position sensor, the VFD can attempt to increase motor power (by increasing AC drive frequency) when the motor slows due to torque loading.

-- Woodworking from an engineer's perspective

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Redoak49

2890 posts in 1823 days


#4 posted 03-08-2017 11:16 PM

I have a Hegner scroll saw. I see no advantage to the control scheme and more disadvantages. Sorry…

View NewSaw's profile

NewSaw

5 posts in 279 days


#5 posted 03-09-2017 02:47 AM

Thanks for the feedback. I used it a bit more today and had a luthier over to try it out. He used it in the variable mode and the constant speed mode (over a couple speeds). He also drew parallel wavy lines, cut them, and pointed out that the backside cuts were more ragged using the variable speed. On a positive note, I pointed out that the system was much “calmer” and quieter with the new control. His smile told me that his job is to make good cuts, not have peace in the shop.

That said, I’ll still poke around on this. It works well for other tools, but the scroll idea wasn’t so clear, that’s why I’m asking the experts.

While I’ve done an above average amount of woodwork (that’s not saying much), I’ve done almost no scroll saw work (lots of jigsaw, wore two out). Appreciate the feedback.(edited for clarity)

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NewSaw

5 posts in 279 days


#6 posted 03-09-2017 03:02 AM


The opposite relationship however is quite useful. Variable Frequency Drives can do this, when connected in a feedback loop with a shaft position sensor, the VFD can attempt to increase motor power (by increasing AC drive frequency) when the motor slows due to torque loading.

I may be misunderstanding your point, but what our control does sounds similar. Let’s say (for sake of argument) we were cutting a piece of painted wood at a half inch linear per second. The wood has less dense areas, but also some hard knots. With this control, the saw might go at, say, 300 RPM in the light areas, then automatically speed to 1200 RPM when a knot is reached. Although the linear cut rate is the same, the power supplied by the saw is probably 16x different (because we increase torque and speed). (edited for clarity)

View tomsteve's profile

tomsteve

663 posts in 1054 days


#7 posted 03-09-2017 03:34 PM

just my opinion-
a variable speed like that would prolly drive me crazy. theres times in interior cuts where I back up in a cut and change directions- going down into a sharp corner, then back up a bit, make the turn, then come back after the interior is cut out and clean up the sharp corner. I like to have the constant saw speed.
theres other times when scrolling that ill be in a cut and slow down the saw speed to get a little better control.
when cutting 3/4” thick oak, I like a higher saw speed. when cutting 1/4” thick oak, I like a slower constant saw speed- I have better cut control. I wouldn’t like the saw speed changing all the time.

but to each his own.

View CharleyL's profile

CharleyL

221 posts in 3199 days


#8 posted 03-10-2017 07:41 PM

I can see no benefit for having this feature. I like to set the speed based on the blade and type of work that I’m doing, and not have the saw changing speed on it’s own.

Charley

View nrscroller's profile

nrscroller

1 post in 293 days


#9 posted 03-14-2017 07:11 PM

I also have a hegner 18vs with variable speed and I can adjust it to my needs. I see no need for this product, I would never use it. SorryBill

View NewSaw's profile

NewSaw

5 posts in 279 days


#10 posted 03-14-2017 07:29 PM

The feedback is much appreciated. I had to look up the Hegner saws after two replies. That is one nice looking piece of equipment! At least in photos. We have two saws and the one that only goes up/down (sorry, at home ill, can’t see brand) is ready to test. We are at least going to try out both types. Hopefully tomorrow for the second.

As poor of virtual reviews as we received on the scroll saw, the system has worked demonstrably well on other tools. As TheDane mentioned, in regards to scroll saws, I did post here as more of a solution looking for a problem. Who knows, maybe there is a material that responds better with this algorithm. When release time comes, I’ll post in the other forums, since this community seems pretty active. I’m personally more of a wood destroyer (burner) than a wood crafter, so I sometimes post on a wood burning forum. That said, I sometimes run across some, seemingly, unique pieces of raw wood!

View Jim Finn's profile

Jim Finn

2575 posts in 2756 days


#11 posted 03-14-2017 10:01 PM

I run my Hegner scroll saw every day , for ten years, now, and see no advantage to your refinement on a scroll saw. What would be good on a scroll saw is a variable speed induction motor. I think Hegners offers these. I have two single speed Hegners. Most scroll saws have universal motors (brushed) and they are not at all durable, like the Hegners are.

-- No PHD, but I have a GED and my DD 214

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