Cutting a perspex bowl with angle grinder, or ...

[carlyai]

I want to cut about 5 mm of this perspex bowl. I was thinking of using my angle grinder and new blade used for cutting pvc pipe. I know I will have to be fairly accurate.

 

Anyone have another method?

 

Maybe buying some glass paper, wrapping it round a block of wood and using it as a bed to sand it down?

If glass paper is suggested, what's it called in Thai and what grade to use?

Get the brains going Friday morning. ????

[noiceonemate]

use a hacksaw, slow and steady, the heat from the angle grinder will melt perspex and cause it to bind. to the blade.

 

Then tidy up with sandpaper, coarse to fine grit until you get a nice finish.

 

use masking tape to wrap the end and mark your 5mm cut line, stay on the waste side of that line when sawing it.

Edited June 11, 2020 by noiceonemate

[Crossy]

Yes ^^^.

 

Any high-speed tool will overheat the plastic and may cause bubbling.

 

If you know someone with a lathe they could do it in a few minutes, sharp tool, low speed.

 

[Mama Noodle]

Buy about 50 of those glasses first because you're probably gonna mess up most of them before getting a good one. 

[Crossy]

2 minutes ago, Mama Noodle said:

Buy about 50 of those glasses first because you're probably gonna mess up most of them before getting a good one. 

 

Yup!

 

[rvaviator]

To help you support the bowl during the cutting process  - Put a large stick inside it - You need to be careful not to crack the perspex when you try and hold it - Clamp the stick in a vise - I would rotate bowl on the stick while cutting. Polish up the cut when done.

[Andrew Dwyer]

A good way to mark the bowl is to lay a pen or pencil ( a fine fibre tip pen would be ideal ) on a table, measure from the tip to the table top and adjust with sheets of paper or a coaster etc to get your 5mm.

Slide the bowl up to the pen tip and rotate, keeping pressure to mark the bowl.

 

Use a fine blade hacksaw ( 24 tpi ) , wrapping the base of the bowl in a small towel to be able to hold it steady. Use your thumbnail as a guide for the initial cut, it will be easy to deviate !

 

A file, or rasp, would be good to get it down closer to the line if you have one.

 

Glass paper/sand paper/emery cloth will all do the job, if you have a scrap piece of wood, or work bench, tape it down at the corners and “ lap” the bowl (rub the upturned bowl on the paper in a circular motion “.

 

Glass paper etc is available at any diy shop or Mr DIY etc usually near the power tools and drill bit section.

 

The roughest grade regularly available ( 80 grit ) will probably be too rough, start with a 180 grit and buy a finer one ( they go up into the thousands ) to finish it off.

[sometimewoodworker]

3 minutes ago, Andrew Dwyer said:

Glass paper/sand paper/emery cloth will all do the job, if you have a scrap piece of wood, or work bench, tape it down at the corners and “ lap” the bowl (rub the upturned bowl on the paper in a circular motion “.

 

Glass paper etc is available at any diy shop or Mr DIY etc usually near the power tools and drill bit section.

 

The roughest grade regularly available ( 80 grit ) will probably be too rough, start with a 180 grit and buy a finer one ( they go up into the thousands ) to finish it off.

As it’s 5mm to go the abrasive paper/cloth is going to be the best option. But taping down at the corners is likely to be a poor choice as it’s likely to come away from the base material. You need to attach the whole sheet.  Spray adhesive is the fastest, you can use a contact adhesive. 
 

if I were doing it I would use a belt sander or disk sander.
 

The abrasive is available in all the big places either on large rolls that they cut for you or in standard square sheets.

[stouricks]

Go on, tell us all why you need it 5mm shorter.  

[VocalNeal]

To finish the thing off. Lay some sand paper on a floor tile to get a perfect surface. Also easier to get it actually square.

Edited June 12, 2020 by VocalNeal

[northsouthdevide]

I just about remember using perspex in school. 

We cut with a fine hand saw, and used a small polishing machine to smooth it off. 

[carlyai]

3 hours ago, sometimewoodworker said:

As it’s 5mm to go the abrasive paper/cloth is going to be the best option. But taping down at the corners is likely to be a poor choice as it’s likely to come away from the base material. You need to attach the whole sheet.  Spray adhesive is the fastest, you can use a contact adhesive. 
 

if I were doing it I would use a belt sander or disk sander.
 

The abrasive is available in all the big places either on large rolls that they cut for you or in standard square sheets.

I've got a disc sander. Put the sander in the vice and go from there?

[carlyai]

3 hours ago, stouricks said:

Go on, tell us all why you need it 5mm shorter.  

Long time ago there was a smoker in the house who stopped using a smoking implement not allowed any more. I broke the glass bowl and ordered some more perspex ones from China, not realising that there were 3 different bowl sizes, just mm different. So I got bigger balls, I mean bowles. 

Now a friend wants to quit so I want to give him the machine.

Happy?

 

 

[sometimewoodworker]

31 minutes ago, carlyai said:

I've got a disc sander. Put the sander in the vice and go from there?

If you can get it to turn on and run then use 2 hands on the Perspex