Which drill bit type for drilling propylex?

[Wakefield Turntables]

I'm fabricating a rega tonearm board in propylex and need to drill a 30mm hole, can anyone advise / help me on this?

[Light Dependant Resistor]

I'm fabricating a rega tonearm board in propylex and need to drill a 30mm hole, can anyone advise / help me on this?

You need to start with using a small drill bit, and slowly build up to the desired size. also using a drill press
provides much better control. 30mm is a very large size, I have had experience to 20mm drilling stainless steel
You might find there is a specialist drill bit needed. Also initially approaching a engineering workshop
might prove to be very worthwhile, as drill bits over about 12mm start to get very expensive.
Hole type drill bits though used by cabinet makers could provide good answer for 30mm size.

Cheers / Chris

[struth]

We used step drills for perspex etc. Worth investing in them

[Firebottle]

For that size of hole I use a hole punch, like this http://www.ebay.co.uk/itm/Q-Max-Sheet-Metal-Punch-Hole-Punch-30-0-mm-/310198589359?hash=item483946d7af:g:e40AAOSwGvhULPU 7

Although meant for metal I've used these type of punches on other materials without problem.
They do give a very neat hole. :)

[danilo]

Step drill... into a suitable pilot hole.. used in a Drill press does a Perfect hole.
Don't go past your desired step size tho :-)
Odd but extremely useful tools.

[Wakefield Turntables]

Step drill looks like the way to go. I only have a simple battery powered drill, nothing fancy with not much torque! Looks like the step drill could be the way to go.

[YNWaN]

Oddly I don't know Propylex but it seems to be a variant of polypropylene. As such it is likely to be significantly less brittle than acrylic and I would use a forstner bit to cut a hole that size (I've done similar many, many times). A hole saw is another option and possibly better if you don't have a pillar drill (or access to one). You could use a step drill but the exact hole position tends to wander a bit as you step through the cut and you could use a punch (if the material is reasonably thin), but it wouldn't be my choice.

[Wakefield Turntables]

I dont have a pillar drill, it's a boys toy that I'd like. I need to produce a 23mm hole in the Polypropylene for the tonearm mounting pillar, 23mm is quite snug according to Rega so a mm or so either way will be ok.

[YNWaN]

I could cut this for you easily Andrew but timing is not good at present and I have no free time for at least two weeks (perhaps three). If this fits into your timescale then I am happy to do it but I suspect you want to do it 'pronto'.

[karma67]

when i was experimenting with different arm boards for my AR turntable i drilled a hole for my rega arm in wood,acrylic and aluminium using a wood spade bit.

[YNWaN]

Yes, if securely clamped, you could do this, it would be one of my bottom choices though.

Probably would work OK on this particular material..

[struth]

I dont know this stuff, but Ive always found that there is a fundamental risk in it(perspex etc) cracking once in a while. you can do it a hundred times perfect and then pop. doh! Just the nature of drilling hard materials that can crack.... Mirror glass was the worst and most expensive.. Preferred the cnc machine to do it in factory but in field we mostly used step bits on perspex

[Bourneendboy]

Flat bit or take it to a cabinet maker / joiner and ask them to rout a 30mm hole. Either way is a 5 min job and very easy.

[mikmas]

I've done loads of holes in perspex and other rigid sheet plastic and a spade bit does it for me every time (up to 30mm easy). Best with a drill stand but easy enough freehand if you have a steady hand. Clamp a piece of scrap wood behind where you want the hole to stop it splintering or cracking - and don't rush it ... ;)
A pilot hole with approx 2mm bit helps ....

[Wakefield Turntables]

Thanks for all the replied, I've certainly learned a new skill now! Step drill bit got ordered yesterday so the tonearm board should get finished in next few days.

[CornishPasty]

I've done loads of holes in perspex and other rigid sheet plastic and a spade bit does it for me every time (up to 30mm easy). Best with a drill stand but easy enough freehand if you have a steady hand. Clamp a piece of scrap wood behind where you want the hole to stop it splintering or cracking - and don't rush it ... ;)
A pilot hole with approx 2mm bit helps ....


That's the one! The pilot hole makes it easier for the bit to do its job and keeps the thing centred. I use spade bits for drilling out aluminium too. The work piece must be securely fixed to the drill press. Skin being torn off is extremely unpleasant.

[mikmas]

The work piece must be securely fixed to the drill press. Skin being torn off is extremely unpleasant.

Oh yes - always clamp the object firmly. Fitter where I used to work decided to drill an aluminium rail while holding it, bit went straight through his hand :(

[Qwin]

Did you ever get the hole made?

Polyplex is a brand name, its actually Polypropylene (Co-Polymer).

For anyone trying to do the same:
It won't shatter and crack as easily as Acrylic sheet (eg Perspex) but normal drill bits will grab and bite in, not good for thin sheet and a hand held drill. Clamping and a pillar drill is best.
If its an arm board I am expecting it is 5mm or thicker so it will be easier, use slow speed to stop it melting and welding the bit to the job and you will probably get away with a hand held drill. Drills specifically for plastic have a steeper cutting angle so they don't grab but are not available at your average DIY outlet. You could use a boring bar cutter or even a hole saw at 30mm dia, again slow and steady, bit at a time as PP melts at fairly low temperature and the hole saw teeth will clog if you melt the plastic. A chassis hole punch as suggested will work on thin PP providing it is at room temperature and not outside on a cold day, as it goes brittle and will shatter at lower temperature. For the thickness you would be using for an arm board, probably not so good and if it works don't expect it to be neat, with thicker sections you will get white stress marking around the hole as it compresses.

Funniest drilling I ever saw was at a commercial vehicle garage, fitting a tipper body to a lorry chassis. An apprentice was drilling a 3" dia hole in some thin plate using a massive hand held drilling machine. It had hand hold bars either side and he had all of his body weight pressing down over it, when the bit grabbed the drill and the lad span round like a top, he wasn't hurt but couldn't walk in a straight line when he got it to stop as he was so dizzy. :lol:

[Wakefield Turntables]

Yeah I needed the info for when I was restoring a thorens td150. That seems such a long ago now.

[struth]

Did you ever get the hole made?

Polyplex is a brand name, its actually Polypropylene (Co-Polymer).

For anyone trying to do the same:
It won't shatter and crack as easily as Acrylic sheet (eg Perspex) but normal drill bits will grab and bite in, not good for thin sheet and a hand held drill. Clamping and a pillar drill is best.
If its an arm board I am expecting it is 5mm or thicker so it will be easier, use slow speed to stop it melting and welding the bit to the job and you will probably get away with a hand held drill. Drills specifically for plastic have a steeper cutting angle so they don't grab but are not available at your average DIY outlet. You could use a boring bar cutter or even a hole saw at 30mm dia, again slow and steady, bit at a time as PP melts at fairly low temperature and the hole saw teeth will clog if you melt the plastic. A chassis hole punch as suggested will work on thin PP providing it is at room temperature and not outside on a cold day, as it goes brittle and will shatter at lower temperature. For the thickness you would be using for an arm board, probably not so good and if it works don't expect it to be neat, with thicker sections you will get white stress marking around the hole as it compresses.

Funniest drilling I ever saw was at a commercial vehicle garage, fitting a tipper body to a lorry chassis. An apprentice was drilling a 3" dia hole in some thin plate using a massive hand held drilling machine. It had hand hold bars either side and he had all of his body weight pressing down over it, when the bit grabbed the drill and the lad span round like a top, he wasn't hurt but couldn't walk in a straight line when he got it to stop as he was so dizzy. :lol:

Know folk that have broken wrists that way..should always use a slip chuck. Even if you dont breakit the ligamentscan be torn and can be worse.