Is my answer a razor saw?

Hi;

 If it is in a sensitive area as you say. Do This. Do you have any of those very neat odd shaped P.E. Stainless saws I have spoken about? Use them . Some are so thin you will not put strain on the part . T.B.

Don Stauffer

I do sometimes "free up the sprue" when trying to cut off fragile parts.  I cut the sprue in pieces and cut away so that cutting the sprue at the largest feed point is the last cut. Even when I do not cut the sprue parts, when the part has a number of sprue connections I judge which connecting points will stress the part the least, and cut them first, so the final cut will cut away the part without pushing the part against another connection.

I'm with Don on this.

Years of working with Eastern European kits--Mirage from Poland comes immediately to mind--has taught that it's often less likely to do damage cutting the sprue stub off at the runner...letting the removal of where it attaches to the part be done a little more 'surgically'...in my case, usually with a single-edge razor blade. It will do a clean slice, if workable...or pare away wafer-thin slices from the stub with almost no stress, until it can be sliced through.

And as the others have said...good luck!

GlennH, Usually sprue cutters will do just fine with plastic. With resin they are worse than useless, and at times the same can be said for very fragile plastic pieces. The problem with a saw is that even the sawing motion can be too much stress on a piece. Sometimes, you do have to cut everything around the piece away first and then get to work slowly shaving off sprue. I've also had success using a sprue cutter to cut a shallow v into the sprue on two sides. Then I finish with a very fine tooth saw and saw a little from several sides so I'm not driving the saw blade into the sprue and creating too much pressure on the part. If that still seems unlikely to work, I would try heating up an xacto knife like someone else mentioned and slice as close as possible and then use a file to remove what remains. And good luck. Barrett

I do sometimes "free up the sprue" when trying to cut off fragile parts.  I cut the sprue in pieces and cut away so that cutting the sprue at the largest feed point is the last cut. Even when I do not cut the sprue parts, when the part has a number of sprue connections I judge which connecting points will stress the part the least, and cut them first, so the final cut will cut away the part without pushing the part against another connection.

Thanks all for the tips. In searching around I started checking the never ending sprue cutter debate again.. Like anything else every single thing you research is either the best device ever made or the biggest POS ever made. Sometimes I think choices were easier when you did things blindly. I did run across a review of these Meng cutters compared side by side with the Zurons I have and was led to believe were the best things out there. I can't say that for the most part I like them but looking at these I have to think they would not have broken those hair thin suspension parts. https://www.themodellingnews.com/2018/02/tools-tried-n-tested-meng-models-mts.html

Also I checked out those God Hands on Amazon. I've been lucky so far but that company better start policing the venders big time that are selling cheap knockoffs. I have been hearing about that more and more lately and it seems these too have fallen prey. Better to maybe eat the free shipping perk on some things and go straight to the source.

GMorrison

A saw may be the answer. I'm not sure what you mean when you "free up the sprue". Can you cut the sprue as close to the part as possible, and then either scrape or sand the rest of it away?

My thoughts exactly. Or simply cut the sprue nub(s) the part is connected to from the sprue tree and trim with an xacto knife on the cutting mat. That always worked for me. Razor saw would be a bit of an overkill. They’re fine for sawing resin parts or large pieces of styrene.

I use a JLC Micro Saw from UMM-USA. It cuts a very thin kerf and is easy to use. I bought the "Anniversary" set, JLC004 which comes with three blades and a spacer set for cutting parallel lines. Go to umm-usa.com.

In the last ten years or so, I've only replaced two blades, having snapped them by applying too much side pressure. When that happens, I superglue the broken pieces into dowels for some truly small and precise saws for delicate part removal.  

The new "thin jaw" nippers is the way to go.  I recently bought one from Sprue Bros and have found it to do a first-class job on tiny parts.  The jaws are small and extremely sharp, they cut so close to the part that you rarely need to sand off a nub.

However, they are not designed to cut thick heavy sprue.

They are expensive (approx. $40) but should last a lifetime.

Hello Glenn!

I use the razor saw for that and since I started I didn't have any parts break while taking them out. Funny thing is my razor saw is made by me out of an old razor blade that once belonged to my pops. About 20 years ago I have taken a triangular needle file and filed some teeth on that razor blade and it works. I sharpen it a little like once in ten years or so... Also, to save time, when I have a part with (for example) three attachment points, I only saw through one or two, and the rest is then cut with normal sprue cutters. And I usually cut through the small diameter attachment points, saves time, but sometimes if there's problem with space and access, I use the method you described to "free up the sprue" - that works, too.

Hope it helps and please be sure to post some photos of that gun! Good luck with your builds and have a nice day

Paweł

An old Xacto blade heated over a candle can be used to cut the sprue away from the part.  The sprue nub will then be more accessible and not place stress on the part when it is removed.  Personally, I don't like using razor saws for the job because I invariably saw back and forth too roughly (I get impatient) and end up damaging the part.

Or you could use one of those new fangled thin jaw nippers like the Volks Pro-Zetsu or God Hand cutters.  Expensive, but they work.  The God Hand cutters live up to the hype and I have not encountered any delicate part that could not be safely removed from the sprue using this tool.  Paul Boyer recently posted a video comparing various sprue cutters including the vaunted God Hands.

Thanks. I doubt it will be visable at all for the most part once the tires are on. Freeing up the sprue..how to explain. You know when you have a tiny delicate part and it has several points where it's connected to the sprue. Steering wheels or traverse and elevation wheels come to mind. If you just take sprue cutters to the connection points, even the xacto sometimes, it acts as a wedge and the only place to give way is the thinnest point which is always the part. So by freeing up I mean you cut other sections of the sprue so it has some place to go and take the pressure off the frail part.

A saw may be the answer. I'm not sure what you mean when you "free up the sprue". Can you cut the sprue as close to the part as possible, and then either scrape or sand the rest of it away?

Also, a bit of model heresy, but if it's a suspension type part that's not going to be real visible, maybe a whole part with a nub on it is better than two half parts.