Cutting Polycarbonate Tubes?

[HowdyNeighbour!]

I have got some polycarbonate tube stock I need to cut down to size cleanly, perpendicular and to a precise length. Not sure if to use the table saw or band saw or something else? I've got a metal chop saw but not sure if this is going to be too powerful and lead to shattering. Any advice on how to do this safely without cracking or causing too much burring/furring on the exit cuts?

 

[Bingy man]

Not a fan of cutting plastic with power tools - so imo the table saw is not good as I don’t believe the blade would be fine enough,,, similar story with a chop saw . I think the best option is your bandsaw if you can get a suitable blade and the speed is suitable. Most plastic - poly carb ,, Perspex ,, or plastic cladding etc I cut with a fine tooth handsaw . The only powertool I’ve used without causing burning etc is a variable speed multi tool . All plastic reacts differently ( age , type , thickness, temperature etc ) so it’s likely you will need to try a few and go with what gives you the best results.. good luck ..

 

[Lorenzl]

You will have to watch out for it snatching and causing cracks.

You could make a simple cutting jig by making a U shape and a slot at 90deg for a hand saw. I was always told never to cut anything round on a bandsaw. But people do get away with it.

 

[Sideways]

I have cut polycarb sheet, 6 or 8mm thick.
Tool of choice was a tracksaw with the speed dialled down and probably an aluminium / plastic blade,I forget.
I would prefer a sliding mitre saw for tube but with the speed reduced to prevent excess heat / melting.
A bandsaw won't give a clean enough cut.
Polycarb is an impact resistant plastic. It won't shatter like perspex / acrylic but it is soft and there's a risk of melting.

 

[BillK]

I found with a bandsaw that fine tooth made for melting & re-forming, grabbing behind the blade and re-formed chips sticking together down the table insert. A coarser blade and going through quickly worked better, not giving time for the melting & re-forming. Not a neat cut or accurate though. This would usually be 6 to 12mm sheet.
Cut to size stuff looks like some type of circ/table saw pattern on the cut edges, there must be blades that suit it.

 

[ChaiLatte]

We do not know diameter, wall thickness or length required.

For example, cutting a two foot length in a bandsaw could be challenging due to throat capacity.

Large diameter, thin wall may need a shallow cut (so it just penetrates the wall of the tube) and then rotate the material.

If it is small enough, bore a hole through a piece of wood the same as the tube's OD and cut through that at the same time. That will give a burr-free cut on the outside. The inside may still need some deburring.

 

[TheUnicorn]

I'd make up a bespoke mitre box and stop block on a bench, and go through it one at a time with a tenon saw

 

[Blister]

Diamond wheel in a angle grinder , Goggles and good dust protection .

 

[Silfi]

I have got some polycarbonate tube stock I need to cut down to size cleanly, perpendicular and to a precise length. Not sure if to use the table saw or band saw or something else? I've got a metal chop saw but not sure if this is going to be too powerful and lead to shattering. Any advice on how to do this safely without cracking or causing too much burring/furring on the exit cuts?

I would suggest a manual mitre saw (not powered). Easy to set a stop block if accurate repeat lengths are required.

 

[HamsterJam]

I used to cut largish diameter copper and aluminium tubing (used as electrical conductors), precisely to length and square using a fine toothed hacksaw and a straight edged piece of paper wrapped around the tube as a guide.
The trick is to cut a 2-3 strokes against the paper guide, rotate the tube a little and repeat. Continue several times around until you have cut through then clean up with a deburring tool or sharp knife followed by some gentle abrasive. I’m sure the same technique will work on plastic ducting.

 

[Amplidyne]

I don't know specifics.
What I do know is that if I had a lot to do, I'd ask the manufacturers the best way to cut it. Most of them are pretty helpful. If I only had a few, I'd cut them by hand with a fine toothed saw, and clean up as required with varying grades of abrasive.

 

[Fergie 307]

Bandsaw is good, provided you use a fine metal cutting blade and you can run it slowly. Unfortunately that rules out a wood cutting one as much too fast and it will melt.
I have used a sheppach portable chop style variable speed bandsaw and it makes a really good job.
Before I had that I would cut various types of plastic piping using a mitre guide and tenon saw. Not quick but does it well.

 

[Sideways]

To save some speculation, can we have more about the application ? Tube dimensions as others have mentioned and the accuracy and finish requirements. There's a huge difference between handsawn to the nearest mm for a toy and machine cut to 10 or 100x that accuracy with an end that is square and polished for us in some kind of instrumentation.
Thanks

 

[Cabinetman]

And if they are very short pieces they could be cut and faced off on a lathe.
Ian

 

[J-G]

Bandsaw is good, provided you use a fine metal cutting blade and you can run it slowly. Unfortunately that rules out a wood cutting one as much too fast and it will melt.
I have used a sheppach portable chop style variable speed bandsaw and it makes a really good job.
Before I had that I would cut various types of plastic piping using a mitre guide and tenon saw. Not quick but does it well.

I seldom disagree with your words of wisdom @Fergie 307 but my experience is that I have cut 50 & 60mm dia polycarb. tube on my wood bandsaw (3tpi teeth) with no great issue. My dimentioning is never critical though since the component will always be machined to size on a lathe.

Similarly, I cut Delrin in the same way - anything from 5mm to 70mm dia. Tufnol thicker than 3mm also gets cut on the same machine, thinner than that is done on a small bandsaw with a much finer blade.

Yes, of course, care needs to be taken to avoid potential melting but when a second op. is needed anyway that can be less of an issue.

 

[Fergie 307]

I seldom disagree with your words of wisdom @Fergie 307 but my experience is that I have cut 50 & 60mm dia polycarb. tube on my wood bandsaw (3tpi teeth) with no great issue. My dimentioning is never critical though since the component will always be machined to size on a lathe.

Similarly, I cut Delrin in the same way - anything from 5mm to 70mm dia. Tufnol thicker than 3mm also gets cut on the same machine, thinner than that is done on a small bandsaw with a much finer blade.

Yes, of course, care needs to be taken to avoid potential melting but when a second op. is needed anyway that can be less of an issue.

I found similar to BillK, that the semi melted chips tended to stick together and be a pain.
Agree with the second op if you want accuracy. I tend to run the ends against a belt sander with a suitable guide so the end is square. Any melting at the edges simply peels off once hard.

 

[HowdyNeighbour!]

Thanks everyone for all the useful advice, fascinating to read all the replies and suggestions. I just wanted to give feedback to let everyone know what I tried. I should have given more information. 38mm tube with 1.5mm wall thickness, application is to use in 3d printed nerf blasters for the kids and their friends. Dimensional tolerances are not engineering level but tighter than I initially thought.

As highlighted by others, melting and friction welding(?) is much more of an issue than cracking. I don't know if it's just my supply or a common thing, but when sawing polycarbonate it stinks!

I tried on the bandsaw with a v-block. It was very messy and just didn't feel safe, at least with my bandsaw and blade.

I then used stop blocks on a fence, scored the cut line with a knife and then a hacksaw made quick work of it, but there was a lot of time post processing. The work holding was awkward to cut with, a mitre box would have been easier.

Knife cuts were very clean but sawing was a pain, hacksaw was too rough, junior hacksaw clogged too easily.

I was wondering if one of those plumber's pipe cutters, the c-clamp style ones, would also be a useful option but I didn't have one to try.

HamsterJam's suggestions ended up being part of the best method I found by far. I used green frog tape to mark the cut line, and used a knife to score the cut by hand, the tape gives enough thickness to keep the cut accurate by feel alone and you get instant feedback if you wander by seeing tape slivers. Finished the cut by slowly deepening the cut line all around with a gent saw with the tube held on a v-block. 20 secs with a swivel deburring tool and a scrape with a knife was the only post processing needed. The end was cleaner than the factory cut side, square and accurate to length.

 

[Sideways]

A little thread drift if @HowdyNeighbour! doesn't mind ?

Cutting, melting and sticking polycarbonate and acrylics....

I have some (side) slotting to do with a wing type cutter in an elu router that was never blessed with dust extraction so I'm looking to fabricating a simple half round dust hood to fix below the router base and attach a hose from the vacuum.

There are hoods available for later models of the router but they are pretty horrid, fragile things and not optimal for this cut anyway, so I'll play and see where I end up.

Polycarb will be the material of choice but I have some rectangles of perspex handy so will experiment with those first.

First thermoforming.
A trawl of the web gives a range of temperatures broadly 150C to 180C for both polycarbonate and perspex. I tried hot air gun but on quarter inch perspex it's terribly slow.
I then tried 180C in the fan oven and the edges of my samples curled up and bubbled, but at least hot perspex doesn't smell.

(This looks fun if you shine a light into it edge on

150C for 6 to 7 minutes softened the perspex without bubbling or becoming too floppy. I was able to slip it out of the oven on a sheet of paper and press it around my former.

The part bent sample from the hot air gun warmed for about 3 minutes before sinking flat on the tray as if it had never been messed with.

You use what you have and I had some hefty alloy bar of about the right size. Several layers of paper wrapped around provide some insulation and slow the cooling just a little.

Next task will be to trim this back to near 180 degrees and find a thin solvent adhesive to make strong joints with minimal mess. If one glue will do for acrylic and polycarb, that would be nice.

Anyone been here before ?