14 replies to this topic

[thedom21]

I am having a problem with the cutting on my scroll saw. Whenever I try to cut through any sort of plastic the cut seals back up with melted plastic. I have tried blades ranging from 18tpi-25tpi and all yielded the same result. I tried adjusting the speed on my scroll saw.(I have an older model that on has 2 speeds, see picture) and again got the same result. I tried putting oil on the blade and yet again same result. My question to you is what would be the problem?


My scroll saw



The cut on the left was made by my blade-runner and the cut on my right with my scroll saw.


When you break apart the bond the melted plastic has you get this



I couldn't get the camera to focus on the clear plastic so the pics are a little blurry

[snakerbot]

Use a high tpi blade, set the blade speed as low as it goes, and push the plastic through slowly, is what I can offer.

[thedom21]

'snakerbot', on 18 Jan 2012 - 01:35 AM, said:

Use a high tpi blade, set the blade speed as low as it goes, and push the plastic through slowly, is what I can offer.

I used a 25 TPI blade on the lowest speed and fed it through as slow as possible for the cut pictured.

[The lord of fish]

I've had more luck personally with a lower TPI blade, think it was 16 TPI? Feed slowly, I was working with acrylic that loves to snap.

Also clean the sides of the blade, and put some sort of grease on the flat sides (not the back or the teeth) except where the blade connects to the scroll saws, I bought a pack of blades that had some rust on them, that made a lot of friction.

[Curly]

This is a stupid question, but are you sure that's polycarb? Clear plastics have this tendency to be similar. Some Googleing says that wrapping the cut in a couple wraps of clear packing tape on the top and bottom can help prevent melting. Crown tooth style blades are often used for plastic. Candle wax can be used to cool the blade on sharp corners. Perhaps wax paper would do the same?

I'm not in a huge rush for the +bow, so don't rush.

Edited by Curly, 17 January 2012 - 09:17 PM.

[Carbon]

I'm guessing that you have a Dremel 1671, which according to the manual, has a low speed cut of 890 SPM...which is pretty fast. Harbor Freight sells a variable speed adapter for routers that would work for your scroll saw.

[atomatron]

Are you sure the blade was facing the right way?

[thedom21]

'Carbon', on 18 Jan 2012 - 02:15 AM, said:

I'm guessing that you have a Dremel 1671, which according to the manual, has a low speed cut of 890 SPM...which is pretty fast. Harbor Freight sells a variable speed adapter for routers that would work for your scroll saw.

I was thinking about just getting a new scroll saw awhile ago but I guess I should move it up on the list.

'atomatron', on 18 Jan 2012 - 03:03 AM, said:

Are you sure the blade was facing the right way?

I just checked and yes it was facing the right way.

[ice]

I had a similar problem with my scroll saw a while back. I don't know what Tpi my blade is but it's the roughest cutting blade that was available in the size, the package said "For quick rough cuts" and the blades are rather far apart. There's maybe 20 of them on the whole 6" strip. Thats all I can offer.

[Swiftone1990]

In line with what Curly said, I would put something like packing tape over the area to be cut. I was cutting acrylic on a band saw, and it melted kinda like what yours is doing. All the melted bit stayed on the protective sheet and the cut was fine. Slowing it down would be the best I can suggest otherwise.

[238232]

How about slowing the blade speed but increasing the feed rate? Sounds to me like lowering the feed rate would increase the amount that the blade rubs against the material instead of cutting it. More rubbing -> more friction & heat -> melting. I believe a similar thing can happen with mills as well.

Aside from that, packing tape would also be a good suggestion.

[TheSilentRebel]

I've been having the same problem with mine.
All of my polycarb has a protective film on it, but without a protective film on the polycarb, it would melt as it was being cut. I suppose packing tape could be substituted for the film.
If I had to cut something without a film on it, I fed the material EXTREMELY slow and usually I could get it cut without it melting too much.

[modsfornerf]

I use 46 tpi Olson spiral blades and add 2 layers of packing tape and it cuts perfectly without melting the plastic.

Edited by modsfornerf, 19 January 2012 - 04:49 PM.

[proplus]

I have the same problem.
I would usually advance the plastic slower to prevent it from melting.

Edited by proplus, 19 January 2012 - 07:43 PM.

[TxNerfer]

The only advice I can give is feed slower and make sure the blade is tightened properly. I have had issues like that, but they were just due to feeding too fast. Feed slowly and you should be fine.

Also, I've never used anything but an 18.5 tpi blade.