Advanced plastic scratch building tools

Have any questions or tips and advice on how to build those bits that don't come ready made.
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TimberSurf
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Advanced plastic scratch building tools

Postby TimberSurf » Fri Mar 31, 2017 12:11 am

Having just acquired a huge supply of both Wills sheets and thin A4 plasticard, to add to my meagre original stock, I am contemplating building methods. I have done scratch building plastic as a kid, but had no instructions or guide. Turned out similar to my attempts with cardboard, rough and skew. It strikes me that I need some guidance from experienced peeps, which I will duly seek, but first I would like to investigate if anyone has used a bit of technology instead of just a scalpel!
By this I mean the following:-

For a mitred corner, is a special 45 degree cutter available or a 45 degree plane?
Is there such a thing as a hobby electric circular mini mitre saw?
Is there a better method of cutting freehand than with a blade or a scoring tool (that then needs no further filing)?
Has anyone cut out the profile or windows with a bench CNC miller? (PC driven for £200) or done mitreing with one?
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Re: Advanced plastic scratch building tools

Postby flying scotsman123 » Fri Mar 31, 2017 7:51 am

For cutting without further filing, try an olfa cutter. This doesn't give you the ridges you get with a normal blade. For mitred edges I usually just cut the side square on then sand the angle with a bit of p80 sandpaper, doesn't take very long and also gives a really good bonding surface for solvent at the same time.

As for computer controlled, take a look at silhouette cutters. Quite a few folk use them for modelling in plastic, mainly for buildings, although I and a few others have even managed panelled coaches with it.
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Re: Advanced plastic scratch building tools

Postby Bufferstop » Fri Mar 31, 2017 9:51 am

I can recommend the Silhouette cutter for both card and plastic up to about 0.5mm. Some plastic needs multiple cuts with the depth increased each time. Cutting is very accurate, haven't tried it myself but I've seen 1mm high lettering cut from 10thou plasticard.
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Re: Advanced plastic scratch building tools

Postby TimberSurf » Fri Mar 31, 2017 11:57 am

OLFA make a huge range! Do you mean rotary or PB-800 scoring?
I can see that a silhouette cutters could be used on say 20 thou plasticard, but 80 thou Will's? Naaaa

Obviously a CNC router/miller would cut 2mm plastic, but what about a laser? Would a laser melt plastic edges?
At the back of my mind I have a Boxzy, these multi tool CNC's are the same price as one standalone!
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Last edited by TimberSurf on Fri Mar 31, 2017 1:05 pm, edited 2 times in total.
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Bufferstop
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Re: Advanced plastic scratch building tools

Postby Bufferstop » Fri Mar 31, 2017 1:03 pm

Someone will have to design a heated cutter for it :idea:
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Re: Advanced plastic scratch building tools

Postby TimberSurf » Sat Apr 01, 2017 10:44 pm

I have gone off the Boxzy, now I have found out the price! $2,999.00!
Further research shows that 3D printers and lasers are low load on the axis, so are fairly lightweight and therefor cheap. As a miller/engraver "touch" and push against the work piece, they have to be stronger (bigger steppers) and more rigid. So the cheap mdf types are a no no. This means aluminium, and T slot bed (proper engineering! woohoo!) Been looking at the Chinese 3040T @ £300.
3040 T 400W.jpg
3040 T 400W.jpg (27.94 KiB) Viewed 449 times

But I am guessing I would soon want to upgrade to DQ type (ball screws) and/or Z type and then change the 400W spindle motor for a 800W or 1.5KW! (I could make my aluminium servo brackets with it!) This puts us in the £800 ball park! Sheesh, I thought OO engines were dear! Needs a lot more research yet, apparently software is needed on top those prices! A simple wooden "Jig" and my router is looking very attractive at the moment! (or do I need a CNC to make the jigs? lol)

I have cracked it! I buy the CNC and make and sell the jigs to others to pay for it and save them buying one! :D
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Re: Advanced plastic scratch building tools

Postby brit-in-bama » Sat Apr 01, 2017 11:29 pm

working in all kinds of plastics all my life, all I can say is that you have two enemies when machining any plastic,
1, heat caused by high speed tools, and 2, pressure, too much force also creates heat, we cut and drill plastic all the time for different projects, they all have different make ups and characteristics, we use hole saws and spade bits at very low speed that actually cut the plastic, for anything that needs to be a clean cut hole, or a very sharp circle cutter (modified wood cutting tool) if its above 2" diameter,, we use a guillotine for cutting straight pieces or strips, anything else we do either by hand or if its small enough we use a professional vinyl cutter, at a local sign-writers, for me personally I would love a silhouette, but funds arent there at the moment for a new toy, but as I said be aware of what these tools do to plastic (particularly thin sheet) before you spend a lot of money on one. JMHO a dremmel is great for steel and hard stuff like Bakelite, brass, copper, but a dangerous weapon when used on any plastic, slow is the way to go, (unless you have it flooded in a coolant).

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Re: Advanced plastic scratch building tools

Postby TimberSurf » Sat Apr 01, 2017 11:55 pm

All these CNC machines come with variable speed, either PWM for DC or an industrial inverter for the larger Wattage AC types, I have seen 300 to 8,000 RPM for the PWM and AC inverters go from 400 to 20,000RPM! I would think on a 3mm bit that would be slow enough?
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m.levin
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Re: Advanced plastic scratch building tools

Postby m.levin » Sun Apr 02, 2017 7:25 am

Make your own CNC or milling machine. Could have one knocked together in an afternoon :wink:

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Re: Advanced plastic scratch building tools

Postby TimberSurf » Sun Apr 02, 2017 9:56 am

I think the CNC idea is getting out of hand. Both in terms of cost and learning curve (New software and complex conversions, PC requirements {mine are too modern,no parallel port etc}), though probably the most suited solution, there has to be a simpler one!
For simple straight line cutting and chamfer cutting, I think I have a solution!. I have an old cordless circular saw, that the battery is shot. I can mount it upside down on a little frame and make a saw table, using a PC 19V power supply instead of the battery. With two metal ball race draw sliders, I can make a slide to hold the work by hand.
For windows, I will investigate further, but I think a Dremel/Router pantograph off the shelf solution may do the trick. I can make a x2 sized template, then replicate square holes repeatedly (will need corners squaring up as the round bit will leave radiused corners)
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Re: Advanced plastic scratch building tools

Postby flying scotsman123 » Sun Apr 02, 2017 10:51 am

To be honest it still feels a little like you're using a sledgehammer to crack a walnut.

For the thin A4 plasticard you mention, scalpels are probably the best tool, the only powered tool I could recommend using word be a silhouette cutter.

Whilst wills sheets are thick, a circular saw seems overkill, and I suspect will still heat the plastic too much and cause rough edges. When I said olfa cutter all I meant was something like this:

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Just score a few times then snap, you get a nice clean edge. For things like window openings a few well placed hand drilled holes will help you snap them out. And for chamfers, just a bit of rough sandpaper, the angle doesn't have to be exact.
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Re: Advanced plastic scratch building tools

Postby TimberSurf » Sun Apr 02, 2017 12:54 pm

flying scotsman123 wrote:To be honest it still feels a little like you're using a sledgehammer to crack a walnut.

Not really! The techniques your quoting were being used 40 years ago! Surely we have moved on since then?

I agree a sharp blade is the answer to plasticard, however, although good for large area coverage, plasticard still needs a thick styrene (or similar) backing for structural strength, this means cutting (windows/doors) twice and leaves the issues of edges of apertures without brick pattern and are twin material.

The "Olfa" scoring tool, I have had for 30 years! Its called a hacksaw blade wrapped in PVC tape as a handle with the raked sharp end cut in by a metal grinding disc, I have been using that in industry forever.

The silhouette cutter may be great for plasticard (see above issue), but wont touch wills thickness.

Drilling holes for windows is just time consuming and ultimately just means we are back at hand filing them, exactly what I am trying to get away from (imprecise/requires skill and time)

The likes of routers and dremel are to fast and will melt the plastic, a circular saw has a much slower peripheral speed and I can reduce it with a PWM controller from my 19v or just use 12V on the 18V cordless.

Chamfering, I want a precise bevel, so will use the saw bench at 45deg

Another idea might be to use an oscillating saw (multi tool) to cut in windows?
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Re: Advanced plastic scratch building tools

Postby Dad-1 » Sun Apr 02, 2017 8:48 pm

I tend not to use Wills materials as they're thick, hard and difficult to cut.
Why have 45 degree corners when a double skin with overlap can give nice
tight corners ?
Oh yes you need to cut with an accuracy of better than 0.5 mm for your plain
plasticard inner shell, but the embossed laminate for the outer is easy to trim.
It may be an old fashioned way, but easy, cheap, and effective.

I think many of my old photos have 'gone' now, but I'll have a look.
Have a look here ..... Nothing wrong with traditional methods.
viewtopic.php?f=5&t=41424&start=195#p565316
That corner should be 'tight' enough for you.

Geoff T.
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a

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Re: Advanced plastic scratch building tools

Postby Bufferstop » Sun Apr 02, 2017 11:32 pm

I agree about the Wills stuff, but as one of the joys of age I'm discovering that repetitious cutting of small rectangles, even if it's quite light cutting, tires my wrists, hence the help from the cutter is appreciated. 200 or 300% zoom and a mouse is much less tiring on wrists or eyes. If there's a tool which enables you to do better work it's always worth investigating. Hence my current explorations in 3D.
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Re: Advanced plastic scratch building tools

Postby timbologist » Mon Apr 03, 2017 1:46 am

TimberSurf wrote: Been looking at the Chinese 3040T @ £300.


Don't by the T suffix as they have trapezoid screws and really bad backlash compensation.
Only by with ball-screws, you are better of paying more and getting a 6040 with the bigger motor and bigger steppers.
It all depends on what you want to do with it, but future proof if you can afford it.

Each of the different tools and machines mentioned in this thread have there specific use, nothing does it all properly.
I have access to them all even a silhouette cutter, the wife's toy.

Timbologist


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