Any tips on cutting a neat hole in plastic sheet material?

viaEstrecha

viaEstrecha

Spanish metre gauge in G scale (on the cheap)
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Bit of a newbie question, but has anyone any tips on cutting an accurate and crisp largish hole in foamboard and styrene sheet? I need to make 4 holes of 15mm diameter for the cab porthole windows on my freelance build, which is a bit limiting as I have only flat blade, auger and masonry drill bits in that size! Oh, and a step drill bit, but not a vertical drillstand or pillar drill. My best idea so far is to make a small pilot hole and attempt to hold the flat bit as steady as possible and hope it does not wander like usual when the bit immediately makes its own large 'pilot' hole, deeper than the plastic sheet.

But I just feel there has to be a better way to go through thin sheet, such as clamping the material between something else and perhaps using another bit more creatively? Any suggestions from skilled scratch-builders, please?
 
Have you considered a hole saw attachment for your drill? You can buy sets from places like B&Q, Wickes, Toolstation, Screwfix, etc. and they make neat holes in wood and fibreglass, so ought to do what you seek.
 
How thick is the sheet? I use a sharp x-acto blade around a cylinder of appropriate diameter.

Once the main line is scribed deeply, break the very tip off and now you have a narrow chisel, used backwards will chisel out a cut into what is left of the styrene. the finished edge is impeccable.

Greg
 
How flexible /thin is the material you are drilling?
If clamped to a piece of close-grained wood, then a small pilot hole, then a (sharp) flat-bit.

Else a slightly oversize hole in the supporting piece of wood, and the step-drill.
But you need to clamp the work, and ideally a drill-press, of some sort..
Even a cheap 'drill-stand' for a conventional drill, should be adequate.

PhilP
 
Greg Elmassian said:
How thick is the sheet? I use a sharp x-acto blade around a cylinder of appropriate diameter.

Once the main line is scribed deeply, break the very tip off and now you have a narrow chisel, used backwards will chisel out a cut into what is left of the styrene. the finished edge is impeccable.

Greg
Click to expand...
Not sure yet: for other parts of the cab I'm using the Spanish favoured method of 3mm foamboard clad with 10 thou plasticard so I can emboss rivet heads with a tailoring tool, but for the cab ends with windows, I'm considering just pieces of 80thou plasticard. Interesting method, which I think will come in handy if I am brave enough to try making a couple of smaller rectangular footholds, but I'll certainly see if I can attempt it.
PhilP said:
How flexible /thin is the material you are drilling?
If clamped to a piece of close-grained wood, then a small pilot hole, then a (sharp) flat-bit.

Else a slightly oversize hole in the supporting piece of wood, and the step-drill.
But you need to clamp the work, and ideally a drill-press, of some sort..
Even a cheap 'drill-stand' for a conventional drill, should be adequate.

PhilP
Click to expand...
Probably 80thou. I can normally bodge with a steady hand on the drill but you've got me wondering if I ought to invest in a drill-stand just in case - money spent on tools is seldom wasted.
Ralphmp said:
Have you considered a hole saw attachment for your drill? You can buy sets from places like B&Q, Wickes, Toolstation, Screwfix, etc. and they make neat holes in wood and fibreglass, so ought to do what you seek.
Click to expand...
I'd forgotten those, yes I have a set but the ones I have are a bit coarse and my smallest diameter blade is 25mm. Typical!
 
maxi-model said:
There are a few options here https://www.amazon.co.uk/s?k=small+...254938&tag=googhydr-21&ref=pd_sl_1fglebf2hh_e
Agree with a dimond cutter, however you might have issues with the plastic melting, even with a slow rev setting. However, I use one of these https://www.amazon.co.uk/ATPWONZ-Co...ocphy=1006579&hvtargid=pla-422751481378&psc=1 Although you are right on the limit, in practical terms, at 15 mm dia hole. Max
Click to expand...
I'd never seen either of those, thanks. The compass cutter looks most interesting as I have struggled a bit in the past with cutting accurate arches by hand for buildings, and it ought to be better than my first effort at trying to shape the cab front over the boiler, too. Think that one will find its way on to my Amazon Wish List, even if it might be too big for the cab windows!
 
Try searching for Wad Punches on evilbay, one use is to cut automotive gasket material.

Single
www.ebay.com.au

Maxigear 15mm Hollow Punch - Wad Punch (19/32") 9336329003110 | eBay

Find many great new & used options and get the best deals for Maxigear 15mm Hollow Punch - Wad Punch (19/32") at the best online prices at eBay!
www.ebay.com.au

Or a whole set
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Hollow Wad Punch Set 9 Pce RENNSTEIG Made In Germany Automotive Trade Quality | eBay

Find many great new & used options and get the best deals for Hollow Wad Punch Set 9 Pce RENNSTEIG Made In Germany Automotive Trade Quality at the best online prices at eBay!
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Trapanning tool is what you need
 
Paul M said:
Have you tried a leather punch of the appropriate size?
Click to expand...
I've used one to make tiny lamp lenses from clear acrylic but 15mm through 80thou plasticard might be a touch big. Awkward size, that. Current Plan A is to use the new drill stand (arriving at the weekend) nice and slowly with a brand new bit, with the sheet well clamped to a support . Plan B will be an assortment of all the other suggestions! I'm going to cheat and use cast spectacle frames on the exterior, so the surrounds should look OK, though the challenge for me will now be making two holes that line up >:)
JimmyB said:
Trapanning tool is what you need
Click to expand...

For brain surgery on the operator? :rofl: Not sure about that for that size of hole, though.
GAP said:
Try searching for Wad Punches on evilbay, one use is to cut automotive gasket material.
Click to expand...
Wow, something else new to me. I suspect it could work and whilst I'd be very tempted by a tool I could use with my lump hammer, it does seem a tad pricey for a one-off job, I think. ;)
Henri said:
Why not use a file? I used one on all the openings in this tram body.
View attachment 304219
View attachment 304220
Click to expand...

That I do like very much and there are a couple of places on my model where I'll need to do something very much like that. So that has been done by eye with a small hand file only? I'm a bit lazy and had intended to cut close to the shape and then finish off with a Dremel and set of diamond burrs - would that work, do you think?
 
viaEstrecha said:
That I do like very much and there are a couple of places on my model where I'll need to do something very much like that. So that has been done by eye with a small hand file only? I'm a bit lazy and had intended to cut close to the shape and then finish off with a Dremel and set of diamond burrs - would that work, do you think?
Click to expand...
Yes they're all done by eye and a small hand file. I think they're called locksmith files (that's how we call them in Dutch).
I tried to use a Dremel but I found out even the lowest speed did melt the plastic too much, I found the process too uncontrollable. Adding that I have an imitation Dremel, not a real one so maybe a real one can be tamed in speed to prevent melting of the plastic?
 
GAP said:
Try searching for Wad Punches on evilbay, one use is to cut automotive gasket material.

Single
www.ebay.com.au

Maxigear 15mm Hollow Punch - Wad Punch (19/32") 9336329003110 | eBay

Find many great new & used options and get the best deals for Maxigear 15mm Hollow Punch - Wad Punch (19/32") at the best online prices at eBay!
www.ebay.com.au

Or a whole set
www.ebay.com.au

Hollow Wad Punch Set 9 Pce RENNSTEIG Made In Germany Automotive Trade Quality | eBay

Find many great new & used options and get the best deals for Hollow Wad Punch Set 9 Pce RENNSTEIG Made In Germany Automotive Trade Quality at the best online prices at eBay!
www.ebay.com.au
Click to expand...
That's the sort of thing I meant, same as a leather punch, but bigger
 
viaEstrecha said:
I've used one to make tiny lamp lenses from clear acrylic but 15mm through 80thou plasticard might be a touch big. Awkward size, that. Current Plan A is to use the new drill stand (arriving at the weekend) nice and slowly with a brand new bit, with the sheet well clamped to a support . Plan B will be an assortment of all the other suggestions! I'm going to cheat and use cast spectacle frames on the exterior, so the surrounds should look OK, though the challenge for me will now be making two holes that line up >:)


For brain surgery on the operator? :rofl: Not sure about that for that size of hole, though.

Wow, something else new to me. I suspect it could work and whilst I'd be very tempted by a tool I could use with my lump hammer, it does seem a tad pricey for a one-off job, I think. ;)


That I do like very much and there are a couple of places on my model where I'll need to do something very much like that. So that has been done by eye with a small hand file only? I'm a bit lazy and had intended to cut close to the shape and then finish off with a Dremel and set of diamond burrs - would that work, do you think?
Click to expand...
As Henri says, it would probably melt the plastic, but there's also the chance that the plastic would tear or split if not held down sufficiently
 
Henri said:
Yes they're all done by eye and a small hand file. I think they're called locksmith files (that's how we call them in Dutch).
I tried to use a Dremel but I found out even the lowest speed did melt the plastic too much, I found the process too uncontrollable. Adding that I have an imitation Dremel, not a real one so maybe a real one can be tamed in speed to prevent melting of the plastic?
Click to expand...
Needle files or more accurately warding files

 
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