Cut off saw

[ROY FERGUSON]

I was having problems trying to use a small miter box to cut structural shapes. I went searching for an alternative and found this 2 inch cut off saw at Harbor Freight.

There is a vise that will move from 90 degrees  to 45 degrees to hold stock .

 

[Jim N]

Very cool.  Thanks for sharing.

[Jantrix]

Please let us know how it does. I'd be concerned for the cutter melting plastic as it cuts.

[ROY FERGUSON]

I have cut some 5/16 H shapes and when I removed from the vise there was a small about of what appears to be melted plastic left on the ends.

I scraped it off with hobby knife.

Residue left from cut

 

Edited May 22, 2018 by ROY FERGUSON

[Jantrix]

But a nice clean cut after the melted residue was trimmed away?

[ROY FERGUSON]

I am not getting clear photos so here is another of the cut then after  I scraped away residue.

A clean cut with little effort to clear away the residue.

Edited May 22, 2018 by ROY FERGUSON

[crazyjim]

Stained glass people use a miniature 2" table saw.  The blade is very fine (many teeth) that might work well for cutting styrene.

[BigTallDad]

2 hours ago, crazyjim said:

Stained glass people use a miniature 2" table saw.  The blade is very fine (many teeth) that might work well for cutting styrene.

Keep in mind there's a difference between the saw being discussed in this topic (also known as a mitre saw) and a table saw. The blade used for cutting glass is typically a diamond-tipped blade.

As a last resort, one can always cut the plastic 1/32" longer, then sand to length.

[Jantrix]

14 hours ago, ROY FERGUSON said:

I am not getting clear photos so here is another of the cut then after  I scraped away residue.

A clean cut with little effort to clear away the residue.

Thanks Roy. I will look for this. 

[crazyjim]

The blade I was referring to Ray, is used to cut zinc came, not glass.  I thought a finer tooth blade might cut styrene smoother.

[dartman]

That's an OK saw,never used it for plastic but works great on brass tubes.......

[Pete J.]

Just from experience with all kinds of saws, it is about a lot of factors.  Feed rate and friction are the two biggest factors because plastic melts at a very low temperature and that causes a lot of the issue you describe.  Any time you use a power saw on plastic you run the risk of melting the plastic.

Unfortunately the cutoff saw you bought does not have a speed control  and frankly I've never seen one with a speed control,  but you could probably slow it down with a dimmer switch added between the outlet and your saw. Unfortunately that method slows it down but also reduces the torque the motor produces.   Run the saw as slow as you can an still have enough power to cut and just ease it through the plastic.  Also and some lubricant.  A few drops of dishwashing soap in water would work well and not contaminate the plastic. 

 Then you have to consider the teeth in the blade.  On a small saw like this the teeth are generally not very sharp  but the more and finer the teeth the smoother the cut, but also the more power it takes to run the saw.  This is all a balancing act.  

[BigTallDad]

2 hours ago, Pete J. said:

Unfortunately the cutoff saw you bought does not have a speed control  and frankly I've never seen one with a speed control,  but you could probably slow it down with a dimmer switch added between the outlet and your saw.

If you use a dimmer switch, you run the risk of burning out the saw motor because of the initial low voltage (and high current needs of the motor) when the switch is turned on and left at a low setting...that's why brown-outs are hazardous to electrical appliances. It would be better to use a speed control for a ceiling fan, which functions opposite of a dimmer control (when activated, the control starts at max speed, then you slow it down).

[TarheelRick]

2 hours ago, BigTallDad said:

If you use a dimmer switch, you run the risk of burning out the saw motor because of the initial low voltage (and high current needs of the motor) when the switch is turned on and left at a low setting...that's why brown-outs are hazardous to electrical appliances. It would be better to use a speed control for a ceiling fan, which functions opposite of a dimmer control (when activated, the control starts at max speed, then you slow it down).

I had this same issue addressed several years ago on another long gone forum.  I needed some way to slow down my Black&Decker grinding tool (at that time a poor man's Dremel).  It only had one speed.  I asked for ideas on that particular forum and was told the same thing.  However I already had the pieces needed (dimmer switch, plug-ins, wire, etc) and built an electrical box with the dimmer switch.  I have been using it now for at least 15 years and have had no trouble with burning out the motor.  Maybe I have just been lucky.

[BigTallDad]

Or you could get one of these at Harbor Freight. I have one permanently mounted on my router table, and it works well. It has a three-way switch: center is off; left is variable, right is full speed.

Another nice thing is there is no wiring skills required. Plug the unit into a standard outlet, then plug the tool into the unit. Even I can handle that!

Edited June 6, 2018 by BigTallDad

[BigTallDad]

On 5/23/2018 at 8:33 AM, crazyjim said:

The blade I was referring to Ray, is used to cut zinc came, not glass.  I thought a finer tooth blade might cut styrene smoother.

I've never used zinc came, only the lead.

[crazyjim]

I use zinc for the outer frame.  Stronger & straighter than lead.

[Pete J.]

I noticed a post on a "more teeth = smoother cut"  and with plastic more teeth can be a problem.  Yes, more teeth means a finer cut, but it also means more heat which is just what you don't want with plastic.  If you add teeth, you need to slow the blade down to stop the heat generation and melting.  Although it seems counterintuitive, with plastic, fewer teeth can mean a smoother cut with less melting. 

[BigTallDad]

18 hours ago, Pete J. said:

I noticed a post on a "more teeth = smoother cut"  and with plastic more teeth can be a problem.  Yes, more teeth means a finer cut, but it also means more heat which is just what you don't want with plastic.  If you add teeth, you need to slow the blade down to stop the heat generation and melting.  Although it seems counterintuitive, with plastic, fewer teeth can mean a smoother cut with less melting. 

Exactly!

Another approach is flipping the blade so it cuts in the "wrong" direction and results in a less aggressive cut.

[Straightliner59]

Man, I gotta get me one of these! I'm thinking a Dremel speed control (since I already have one, anyway) would work.

 

Edited July 11, 2018 by Straightliner59

[Deuces]

You could try candle wax for lube on the blade.... But then you would have to scrub the wax off the part you plan to glue together and paint.....