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Author Topic: How do I cut a 3mm slot in 1mm plastic?  (Read 7089 times)

dougal99

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How do I cut a 3mm slot in 1mm plastic?
« on: August 24, 2007, 07:51:48 PM »

Hi all,

I am currently building Model Slipway's kit Sentinel which requires some small slots 3mm long and approx 0.5mm wide to be cut into 1mm plastic. I have been trying it out on scrap but cannot achieve the required width. I always end up with a slot that's too wide.

I have been drilling 3 x 0.5mm holes and trying to join them with a sharp pointed blade. Has anyone got ideas on how I might achieve the requirement?

Ta

Doug
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Tug-Kenny

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #1 on: August 24, 2007, 08:24:17 PM »



I have not tried such a small slot myself, but would suggest a pointed surgical scalpel.

You could score the outside edge carefully and also score across the inside from corner to corner, creating a cross. Then push the centre of the cross to break the scored lines outwards. Should then not need trimming, as the 1mm breaks cleanly.

Best of luck and mind you fingers.


Ken
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John W E

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #2 on: August 24, 2007, 08:45:55 PM »

Hi there dougal 99

Have a try at this method:

clamp two steel straight edges in the vicinity of where you want the slot - by using either G clamps, clothese pegs, or whatever - clamp the two straight edges 3mm apart and this will give you a good edge to cut along with the scalpel blade, after first drilling 2 x 3mm holes either end of the length of the slot.  Ive included a 'scraggy' sketch  :D to try and explain it.

aye
john e
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Colin Bishop

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #3 on: August 24, 2007, 09:07:11 PM »

Use 1/64th ply! I'm building a Dean's steam yacht Medea at the moment which requires a lot of cutting out of plasticard. Give me plywood every time!
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dougal99

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #4 on: August 24, 2007, 10:06:58 PM »

Guys,Guys

Thanks for the input. However, the slot is 3mm by 0.5mm thats .15 square cms. No room for cross cuts or clamps as the superstructure is already built thus no plywood.

Any other ideas?

Doug
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Bunkerbarge

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #5 on: August 24, 2007, 10:13:24 PM »

I would have a play with a .5mm drill bit or an end mill if you can get one and run it along a straight edge. 

Set the depth somehow with a collar or something and see what happens.
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Colin Bishop

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #6 on: August 24, 2007, 10:16:04 PM »

I think the only way to do it would be to lay a straight edge of some sort along the length of the slot and run a 0.5mm drill in a power drill along it for 3mm. Then use a very sharp pointed scalpel to clean it up. It's such a small hole that you will have trouble in plastic whatever method you use. It's too small to make up a punch.

Snap Bunkerbarge!
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DickyD

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #7 on: August 24, 2007, 10:17:24 PM »

Guys,Guys

Thanks for the input. However, the slot is 3mm by 0.5mm thats .15 square cms. No room for cross cuts or clamps as the superstructure is already built thus no plywood.

Any other ideas?

Doug
It's actually 1.5 square mm
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Bunkerbarge

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #8 on: August 24, 2007, 10:19:03 PM »

I think the only way to do it would be to lay a straight edge of some sort along the length of the slot and run a 0.5mm drill in a power drill along it for 3mm. Then use a very sharp pointed scalpel to clean it up. It's such a small hole that you will have trouble in plastic whatever method you use. It's too small to make up a punch.

Snap Bunkerbarge!

Great minds etc...etc...
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dougal99

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #9 on: August 24, 2007, 10:22:35 PM »

Thanks for the input I'll see what I can rig up with a drill as I don't have access to a milling machine.


Doug
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HS93 (RIP)

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #10 on: August 24, 2007, 10:58:19 PM »

If you are drilling in plasticard especially with very thin drills have a small squeezy bottle of water handy and drip it as to the drill it stops the drill picking up plastic when it gets hot and sticks to the drill ,so you get a clean hole as the drill does not grow in dia with plastic, it only needs odd drips .
Peter
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meridian

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #11 on: August 24, 2007, 11:21:02 PM »

I have an X-acto hand saw with a 0.35 mm blade. This produces a slot which is about 0.5 mm wide.
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Colin Bishop

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #12 on: August 24, 2007, 11:26:10 PM »

Yes, but I bet the blade is more than 3mm long. OK if it's an open ended slot but I got the impression that it's a closed one - or am I wrong? If it is open then the Xacto knife saw blade would certainly do the job as you say.
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Peter Fitness

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #13 on: August 25, 2007, 12:52:54 AM »

I am intrigued as to where on the Sentinel these small slots are. I built one a couple of years ago, and don't recall being faced with this problem. Mind you, my memory isn't so good now either.............what were we talking about??? ??? ;)
Peter.
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Tug-Kenny

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #14 on: August 25, 2007, 10:31:48 AM »


Is this piece of plasticard allready fixed on the boat ?

Can you take a picture for us. It's intriguing. If you went wrong, then is there a damaged piece still on the boat ?

Sort of problem to get the old grey cells moving. ( as Pieorot would say).. O0


Cheers...Ken
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HS93 (RIP)

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #15 on: August 25, 2007, 10:38:10 AM »

Could you laminate a piece of brass shim on top with the slots in it.

Peter
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tigertiger

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #16 on: August 25, 2007, 03:35:41 PM »

If you have more than one slot it sounds like you need to make a jig.

A possbile solution.

A piece of brass sheet (or other metal) and carfully drill the the two 0.5mm holes at 2.5mm centre to centre. drill other holes in between and then use a 0.5mm router of the drill bit as a router.
On second thoughts if you have a pillar drill and one of those sliding vices you could use a piece  of mild steel. As it is thicker and harde than brass you will get a better vertical.

The jig can then be clamped onto the plastic sheet.

But I am sure somebody can come ouy with something smarter than this.

But at 0.5mm I would not want to paint it.
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DickyD

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #17 on: August 25, 2007, 04:19:40 PM »

How do you paint a 0.5mm hole ?  ???
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bigH

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #18 on: August 25, 2007, 05:08:12 PM »

   Don't know if this helps Doug but I bought a couple of those cheap little wooden handled chisels, you know, the type you find in every pound shop.
  I then ground the blades down to whatever size and shape that I neededthe blades are as close to 1/2 mm as dammit in thickness and you can grind them down in width no trouble......
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omra85

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #19 on: August 25, 2007, 07:23:26 PM »

Thought you'd have known that Dicky
Carefully mask round the hole - spray - remove masking - voila! A painted hole!   :D :D :D :D :D ;D

Danny
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dougal99

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #20 on: August 25, 2007, 10:45:17 PM »

The slots/holes are required to accept brass 'u' pieces which are the supports for the vertical handrails either side of the ladders. There are four supports on each side of the superstructure each requiring two slots. The superstructure is already built as I hadn't considered the railings etc until now. Moral RTFM.

Peter, bummer I was hoping you'd come along with ready solution.

Tiger Tiger, your solution was how I was going to try it unless somebody gave me a better idea.

I can't get into the workshop for the next few days, painting the floor, so the job will remain on hold till then. I'll let you know all how I get on.

Bigh, your idea is also an approach I thought about but I have no grinding wheel (yet!).
 
Thanks everybody for the help.

Doug

PS Omra85, I tried your method of painting holes but they all come out as the same colourless space.  O0
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DickyD

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #21 on: August 25, 2007, 10:53:48 PM »

PS Omra85, I tried your method of painting holes but they all come out as the same colourless space.  O0

I told him it wouldn't work Doug, but you know what these youngsters are like. ::)
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bigH

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #22 on: August 27, 2007, 05:35:42 PM »

  My uncle used to make holes for a living, he swears that he made the first 1,000 holes to fit in Polos, I know he used to bring sacks full of holes home for us idiots to play with.   I woildn't lie to you fellas, honest.... ;D  ;D  ;D
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Colin Bishop

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #23 on: August 27, 2007, 05:42:42 PM »

Yes, but was he any good with slots, I believe different qualifications were needed?
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bigH

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Re: How do I cut a 3mm slot in 1mm plastic?
« Reply #24 on: August 27, 2007, 06:15:15 PM »

   I do not know if he did slots Colin, he fell into one of his own holes one day and came out in Oz.   It took him 2 wks to get back and his boss sacked him for leaving his hole without permission, he went off and joined the legion and the last we heard was that he was making upside down umbrellas.   Harry
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