Cut off clear sprue parts without cracking?

I will usually clip off a couple mm section of the sprue to go with the clear part. This gives me more room the work with. Now depending on the fragility of the clear piece, I'll use a number 11 exacto knife to cut off the remaining sprue. Or attempt to score the edge as finely as I can with the back edge of the number 11. Then finish up with sanding. 

Same as Bruce, plus often can snip off smalls bits of the remaining sprue at time, working down to where you want to be.

One of the advantages to this method is by making the first cut away from the piece, you can see how the clear plastic is going to react. Watch for a crack or split to develop, see how it acts. This tells you how to proceed.....more snips if minimal cracking/splitting or proceed to Bruce's method with a good blade if otherwise.

IMO, good quality sharp sprue cutters are a must here.

I use a fine spiral blade on a jewelers saw.  Kills two birds with one stone, and no cracking.

I also cut the sprue in pieces near the part.  Other thing is, in extreme cases I will cut sprue attachment points with a knife.  To prevent breaking I cut them on a small block of particle board, arranged so part is on surface of block, sprue hanging over edge. That way the sprue attachment point is resting on black, and you will not bend it as you cut through.

I use a fine razor saw, and cut a couple of mm away from the part, while bracing the part on a block, as Don describes.  Then I sand away the excess down to the part to neaten up.

           Hutch.

For really brittle plastic, I go with a razor saw.

For pretty much everything else...I've found that the cheapo 'keychain' finger-nail clippers from the drug store often cut more cleanly than purpose-made sprue cutters. They're usually great until I forget, and use them to clip wire or PE.

But it doesn't hurt much to replace them.

Thanks everyone for the replies. I'm surprized no one mentioned using the 'heating the cutter edge' option. 

I like the simple solutions like using a nail file. My personal belief is that you can put so much of what's around you to good use, you should only go out and buy specialized items if it's necessary.

Keep the replies coming if you have anything more to add! 

ohms

Thanks everyone for the replies. I'm surprized no one mentioned using the 'heating the cutter edge' option.

I've done it. Long time, as in like 50 years ago. Heating Exacto blade with a flame, which never worked, then on to a purchased tool that looked like and exacto blade in a holder on steroids with a cork ring to hold onto and an electrical cord to plug it in.

Ruined everything I touched with it. I remember it'd set for months and I decide to try it on something else, which would get ruined too. I never throw anything out, I'm surprised I don't still have that useless tool.

I ruined a part last summer trying to modify it using heat. Beautiful half-done model still on hold due to another brilliant idea by yours truly to "lets heat 'er up!!"

Just my opinion, but it's been my experience that with the possible exception of stretching sprue, heat and styrene models just don't mix. I'm amazed I have yet to ruin something drying paint with my hair dryer!

I use my Tamiya snippers and haven't had a problem yet. Just use the very tip, don't go in deep with the snippers.

I would expect heat to not be a good idea to use.  You would likely deform or take away to much, also you likely get stringing and dragging away of some more than you want to.  The plastic as it sets up again will likely be harder and more brittle.  I don't know if you may not also affect the clarity near where the heat was, and certainly risk deforming it.

You need a razor saw. Simple and cheap option. Nothing else will work as well. 

Hi Ohms!

    Listen,You have probably read more of my threads than necessary and wish I would go away. Well, I am gonna keep sharing with you folks till That Place freezes over Or I leave first! I bought two different sets of Photo-Etched saws. They are even different thicknesses. I now use those exclusively to remove clear parts from Sprues. You'd think after all these years Model Rail manufacturers would get it right wouldn't get it right wouldn't you?

    They still create brittle window pieces and flat clear pieces fracture easier it seems. These little saws have saved my bacon more than once. I don't remember the brand But they were over on the hooks at then Hobby Town in the tool section!

 They have stayed sharp after a lot of cutting. You just have to get used to their size and shape. Some have odd shapes with different cutting edge sizes on opposite edges.

Greg

... with my hair dryer! 

 

GMorrison

 

 

Greg

... with my hair dryer! 

 

 

 

 

????

 

 

Ha!!!!

Thanks for the laugh, I needed that today.

BTW, the razor saw suggestion is very good. Now to remember it next time I'm cutting (er, sawing) clear parts off the sprue.

Are the cutters sharp?

Lately I have been cutting the sprue with a knife and a special blade I use just for tasks like that.  I took a scrap block of wood and put a small wood mesa on it so I can rest the part on that mesa without any of the sprue touching the block.  I forget the number blade I am using, but it is a very wide one with the edge along the bottom- it is a very strong one and will not break the point.  I put on my highest power glasses and cut as close to the part as possible, with multiple strokes.  I finish up any sprue glitches with a needle file.

Hi;

 I will have to say, in defense of Sprue cutters.There are good Sharp ones.There are Sharp good ones. But I will not spend the money for "GOD's" own sprue cutters. Way overpriced for the type of tool.

 The saws I spoke of can be replaced or bypassed with some small straight blades I found from X-Acto.They are angled at Forty-Five degrees on each end. One end comes to the point on the tooth side. The other end has the point on the back edge.( No Teeth). I have some that are over ten years old and they still cut good.

      Don't try to cut any kind of metal with them though. Any type of saw made for what we are discussing will not hold up trying to cut metals. They do make some fairly thin Hack-Saw blades But, they are NOT CHEAP!

   I have NEVER tried a hot knife on this operation. Wouldn't think it would work all that well.

Nathan T

You need a razor saw. Simple and cheap option. Nothing else will work as well. 

 

I use the UMM paper thin razor saw and works every time.

Tanker-Builder

I will have to say, in defense of Sprue cutters.There are good Sharp ones. There are Sharp good ones. But I will not spend the money for 'GOD's' own sprue cutters. Way overpriced for the type of tool.

You can lop my left thumb off; I'd miss the thumb but not the osteoarthritis pain. My feet? Take 'me -- they're pretty much useless to me! My brain? It's long past its best-by date, so you can have that too. But my GodHand SPN-120 Ultimate Nipper? Hands off! (Or risk losing a hand.) I am not a religious person, but I recognize fine craftsmanship when I see it, and I know in my heart that my GodHand Ultimate Nipper was personally machined by God Himself! 

On a shopping trip Magic Box Hobbies in Vancouver for modelling supplies, Wendy, the sales person and a modeller herself, suggested buying the GodHand nipper rather than the pair I had picked out, and she warned me that they were expensive. She had given me a lot of useful advice on previous trips, and I had experienced the hazards inherent in spruce cutting, soI took the risk, which I considered to be slight.

I haven't regretted my purchase for a moment. When tool gives me visceral pleasure when I'm using it, I know that I didn't spend too much on it.

Bob