Turning and burning!

[Mr Christopher]

I have just come in from completing my very first proper scroll saw project. A Steve Good Large Gnome. Went fairly well and didn't break a blade . Did get some burning though and would be interested on thoughts as to why. Was using 1/4" and 5/8" ply with No.2 and No.5 reverse blades respectively. Burning was on the thinner stuff. Could it be I'm being too cautious on my turns and need to get round those them scrolls faster?

 

[scrimper]

Strange with most sawing on any type of saw (Circular, bandsaw or fretsaw) you only get burning when the saw is struggling to cut. Have you tried reducing the speed a little? The blades must get hot in use as I do notice on the cutting part of the blade but generally I have not noticed any burning on the work.

 

[martin.pearson]

Burning is caused by friction, heat builds up & the wood burns so it could well be that you are being to cautious & moving the wood to slowly around the bends especially with the thinner stock, you get the same sort of thing with people new to CNC, they set very slow feed rates because they are unsure of what they are doing & don't adjust the speed of the spindle or router.

 

[Mr Christopher]

Strange with most sawing on any type of saw (Circular, bandsaw or fretsaw) you only get burning when the saw is struggling to cut. Have you tried reducing the speed a little? The blades must get hot in use as I do notice on the cutting part of the blade but generally I have not noticed any burning on the work.

Unfortunately I'm unable to adjust the speed as I'm using an older Hegner with single speed. I think it might actually be the old ply and its glue coupled with me being very hesitant to move along the line of cut.

 

[loftyhermes]

Cover your patterns with clear parcel tape, this helps to stop the wood burning, something to do with the release agent on the back of the tape.

 

[scrimper]

Cover your patterns with clear parcel tape, this helps to stop the wood burning, something to do with the release agent on the back of the tape.

We often do this with a bit of sellotape, as you say it does seem to lubricate the cutting, sometimes we also rub some candle wax on the blade.

 

[Cooper]

Cover your patterns with clear parcel tape, this helps to stop the wood burning, something to do with the release agent on the back of the tape.

When cutting perspex or other plastics often the pieces stick together after the cut because the waste melts and bonds the edges back together. Using masking tape solves this, the waxy tape seems to lubricate the cut. So the quoted suggestion may work. It is also easier to draw a visible line on.

I have a single speed Hegner and when I cut thick bits of oak, for example, the blade does get very hot but I've never managed to burn the wood. I have found that the Hegner is so good that the blade only fails after a lot of use when its blunt, it then becomes very hot.

Ply at 5/8ths would be similar to my experience with oak, contrary to the advice above I think pushing hard to cut faster would cause more heat than going slow, though dissipation of the heat generated would be slow with such thick material. I generally use a No. 9 blade and as I said I've not managed to set anything on fire yet!!

Good luck
Martin

 

[loftyhermes]

I find that leaving the protective covering on plastics and acrylics helps prevent the melt back.

 

[Mr Christopher]

When cutting perspex or other plastics often the pieces stick together after the cut because the waste melts and bonds the edges back together. Using masking tape solves this, the waxy tape seems to lubricate the cut. So the quoted suggestion may work. It is also easier to draw a visible line on.

I have a single speed Hegner and when I cut thick bits of oak, for example, the blade does get very hot but I've never managed to burn the wood. I have found that the Hegner is so good that the blade only fails after a lot of use when its blunt, it then becomes very hot.

Ply at 5/8ths would be similar to my experience with oak, contrary to the advice above I think pushing hard to cut faster would cause more heat than going slow, though dissipation of the heat generated would be slow with such thick material. I generally use a No. 9 blade and as I said I've not managed to set anything on fire yet!!

Good luck
Martin

Good advice Martin, thanks for being in touch. I will do what you say and perhaps also practice using a No.7 or No.9 blade

 

[martin.pearson]

Ply at 5/8ths would be similar to my experience with oak

Maybe I read the post incorrectly but the way I understood it the OP wasn't experiencing any burning with the thicker ply, just the thinner stuff.
But I also don't have any experience with scroll saws, I have had a really cheap one kicking about the workshop for years & don't think I have ever used it, in fact I'm not even sure where it came from lol