Screw shortening advice sought?

[georgerkahn]

I picked up a little Beretta 418 .25acp pocket pistol, which came with two boogered screws holding on (original, decent shape) grips. I found a set of replacement screws, ordering and receiving them. Here's the problem: The thread is perfect, and the screw head is ideal. BUT, they're about 3/4s of a turn too long, impacting the grip safety. Being "clever" I applied some packaging tape under grips to make them "fatter" and solve the problem. No go, with three layers of tape -- I NEED to shorten the screws a tad.

My general practice is to screw screw into a nut, cut, file, or grind off excess -- and then unscrew it, to have a chance at my not having messed up threads and enable use. However, these are quite wee metric size of unknown threads per centimeter -- so that plan is not in my works.

I was thinking of chucking screw in a pin vise, and "polishing down" the tip with a stone? However, it seemed smart to check with one of the most knowledgeable persons on this site.

Any suggestions as my perhaps best process?

MUCH THANKS!

geo

[porthos]

drill a hole slightly oversize (.003-.005) in a thin piece of steel or aluminum. lets say a small "bar" 1/2 in. wide by long enough to grab onto with the off hand. stick the screw thru and use a proper size screwdriver in the screw slot to guide and keep pressure while grinding it shorter. i use a belt sander. brownells sold a device called a "screw holder gizzy" don't know if they still do. but you were limited to small sizes

[Drm50]

I have a Brownel Screw Grizzly but fore normal gun screws I redrilled and tapped a set of electricians screw cutters and have pieces of 3/16" flat steel drilled and tapped to hold screw while
using jewlers fine or stone on them. I don't have all the off the wall metric taps & dies so I take
a piece of alumilum as thick as possible for the screw to protrude through. I select a standard bit
about one size smaller than dia of screw threads. Very carefully you can use the screw for a tap in
soft Alumilum. Usually if you are careful in the direction of the strokes of the file , making sure the
pressure applied is tightening the screw this will work well on small screws.

[Petrol & Powder]

Would a small washer under the screw head work without holding the head proud of the grips?

The technique mentioned by porthos would work just fine.

A trip to the hardware store to find the correct metric nut would allow you to use you preferred method of screwing a nut in place before grinding the tip off (allowing the nut to straighten the threads when you remove it).

I've had good luck shortening small screws with just a good fine file, some small scraps of wood, a vise and some careful work.
Clamp two small scraps of wood in a vise with the edges aligned. Select a drill bit with a diameter about 2/3's smaller than the diameter of the screw head. Drill a hole right between the two pieces of wood so that half of the hole is on each piece of wood. The hole doesn't need to go very deep, just enough to hold the head of the screw.

Clamp the screw head in between the two pieces of wood with the threaded portion facing up. Then using a good file, carefully remove a bit of material. It works fairly well if you keep the file at 90 degrees and take your time.

[LAGS]

I have taken ODD size screws, and drilled a hole THRU a piece of thin metal shorter than the length threads you will need.
Drill the hole in the metal that the screw will barely fit thru.
Then I put Johnsons paste wax on the Screw and coat the hole with Epoxy, then insert the screw into the hole and let it cure overnight.
When cured, File the thread end of the screw to the length you will need.
The screw will not be bonded to the metal jig because of the release agent.

[georgerkahn]

Thanks to all -- local hardware store has what may be the correct diameter nut, but not the correct threads-per-cm. A metric nut of correct size was my first choice. I like the suggestions given -- THANK YOU!!! -- and am thinking of the aluminum or hardwood tricks mentioned. In the morning, I may get the nerve up -- at about seven dollars for each of the two screws, I surely do not wish to have to purchase another ;).
geo

[2152hq]

drill a hole slightly oversize (.003-.005) in a thin piece of steel or aluminum. lets say a small "bar" 1/2 in. wide by long enough to grab onto with the off hand. stick the screw thru and use a proper size screwdriver in the screw slot to guide and keep pressure while grinding it shorter. i use a belt sander. brownells sold a device called a "screw holder gizzy" don't know if they still do. but you were limited to small sizes


This is the easiest way to do this job and not damage the threads or the head of the screw by trying to clamp down on them in any way.

The screwdriver blade held in the slot of the screw from the back side keeps the screw tightly in the screwholder (the piece of flat stock scrap metal. Both of which can be easily and comfortably controlled as it's held against a grinding wheel or belt.
Being able to turn the screw while it is in the holder by turning the screwdriver is a plus as you can put a nice even end & finish on the screw stud quickly.

Quick and easy to do.
Making the holder takes as long as it does to drill one hole in a piece of thin flat stock.

If you are concerned about taking too much of the threaded end off in one quick pass,,a trick is to first file a slight taper on the edge of the end to be shortened. Doesn't need to be much, just enough to be able to be seen,,sort of catch the light so you see the facet of the cut.
Hold the screw in your fingers for this and simply file a slight flat on one edge of the thread to show a flat down to the required length.
Make that slight cut/taper as far down the side of the thread as the total amt you want to remove from the entire end of it.

Then when you are working the screw end against a grinding belt or wheel, you simply grind till that slight taper is gone. You are then at the length you wanted.
Works for shortening w/a file or even in a lathe. Better than trying to count threads to be removed from a vise or fixture & continually remeasuring the OAL.

[country gent]

I have drilled the screw size hole thru a piece of flat stock 3/8" -1/2" thick then counter bored for the head to leave a .060 or .090 length of the screw dia. Then tap the counter bore for a set screw. drop screw in hole snug set scre to hold it and you can mount it in vise and file. a mill and cut down or on a magnetic chuck and grind. Apiece of flat stock can be done for all the common sizes 6,8,10, 1/4" nice thing with this set up is thread pitch dosnt matter. I used the shorter set screws that the allen socket went thru and cut the bottom to a full 60* chamfer with a center drill. this squared and centered the screw nicely and helped keep from damaging the head.

[725]

I usually drill and tap some scrap metal, screw the offending screw through so that what ever length to be removed sticks through. Hold it up to a belt grinder or grind wheel, remove the desired length, and then back it out through the scrap metal. Backing it out chases the ground threads so it screws easily back into whatever it's supposed to go in.

[country gent]

If you want a threaded bushing or holder and cant get the tap. drill the hole between shank and head size wax the screw good with several coats of wax and fasten in the hole centered fill with J*B epoxy work in good with a wire and let cure. You can form some pretty good threads with a very nice fit this way. I have used this to form 7/8 14 threads in wood stands for powder measures. Once cured its almost a zero fit thread clearance. A thinner faster cure epoxy might work but test it with your release agent first some will glue thru waxes and oils
If we had to fit a lot of threads at work for something we did it with the plate I described above with a surface grinder. This gave very little burr to remove a very nice flat surface and was easy to control the length.

[edp2k]

2 thoughts:

1. a great source for small metric nuts is a hobby shop, you know, the stores that sells RC cars and planes. Bring along the screw.

2. screw holder for grinding to length:
get a scrap piece of sheet metal strapping (Al, steel, whatever is cheap and handy, or cut it from a larger scrap sheet).
approx. dimensions: 1/2" wide by 12" long.
drill a hole for the screw thread to go into (snug fit) about 1/4 of the way from one end (i.e. 3" from one end).
fold strap in 1/2 (i.e. double it over length ways) so that hold is now equidistant from either end.
spread ends open enough to insert screw thru hole so that when the strap closes back up the screw head is trapped between the
flats and the screw threads are sticking out.

now either tape up strap so that it wont open (and thus the screw wont come out) or
get 2 more 2" pieces of strap and make "clothes pins" out of them and use them to hold the strap shut.
now grind away with a dremel or grinding wheel or file.

debur, then remove from strap.
Done!

[Texas by God]

I made a screw "gizzy" from a pair of tweezers. I drilled one hole for 6-48 and one for 8-40 size. If I can find it I'll send a pic.

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[georgerkahn]

Texas by God (and others) -- I'd love to see your "gizzy"! Taking grips off earlier, I chickened out -- at least for this morning. Re the Hobby Shop notion, the one I tried did in fact have a couple of screw with a "maybe" same thread-per-centimeter, but were MUCH longer, in stainless, and had a Allen-type head. The head would have needed grinding, too -- one of my initial "fixes" was to put a thin washer beneath existing, working screw's head -- but that would raise screw top above adjacent grip. (Plan "B" was the packing tape under grip panels which didn't work... why I'm "here" :) )

I have but a small amount of usable female thread on the starboard (right side, as you hold pistol to land-lubbers) side as the top threads were boogered by the wrong-size screw which a prior owner put in. I *think* if I take just a wee bit off new screws, I can make it work. If the tip of screw was pointed, I could have used my Dremel and it would have worked, I am certain. However, the very fine thread on a very tiny screw exacerbates the challenge, threaded 90*/flat at tip. If I could envision T b G's gizzy, that may be an approach. I'm thinking the hole was drilled in but one arm, with the then closed tweezer now able to work as a vice for screw? Ingenious! I could then barely scarify it with the Dremel, and use a knife blade if necessary to restore the top thread to function. You may have instilled the confidence for me to get the nerve up to try it!
THANK YOU AGAIN!
geo

[Texas by God]

After ruining screws and burning fingers and cussing I saw Brownell's Gizzy. Some one had their thinking cap on. So I farmered my own.

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[georgerkahn]

Thanks again, T b G! I Googled the Brownell Gizzy, and see what you're referring to. Also, watched their accompanying video. https://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/polishing-tools-accessories/polishing-wheels/screw-holder-gizzie--prod599.aspx I hit upon a slight adaptation, as I took a 3" brass hinge, drilling a hole to afford a snug fit for my too-long-screws on one side. I then drilled two holes to afford 8-32 bolts and nuts through the closed hinge, so when the hinge is closed on the screw I wish to shorten it is firmly held -- no lock-tite, etc. needed. Plus, I was able to hold this jig in one hand, while VERY gently applying a disk on a Dremel with the other. Oops -- I forgot to mention I recorded OAL with my Mitutoyo calipers before grinding; I then took ~0.07" off; said a quick prayer, and tried it. PERFECTO!!! It screwed in, is tight, and no longer impacts the grip safety. I then did the same for 2nd (port side) screw; I had difficulty getting this one started, but got out a magnifier and gently beveled (or de-burred?) the tip -- and again, success!

I can put this project to bed, with a smile. And, lots of thanks to all the wonderful persons who took the time and effort to share their knowledge, enabling me to have success with this challenge.

georgerkahn

[edp2k]

FYI What I decribed is Brownell's screw gizzy, same as TexasByGod mentioned :)

Georgerkahn. I like your hinge variant of the Brownell's screw gizzy.

Kudos from a Tech-er (CCT) :)

[georgerkahn]

edp2k -- my apologies for not "getting it" from your sound suggestion. I'm clearly not the brightest bulb in the fixture: I reckon getting the materials (1/2" x 12" piece) threw me for a curve ;). Perhaps with your seed not yet germinated, and T b G's gizzy description -- which I Googled to SEE -- prompted my using the 3" brass door hinge. Matter of fact, I had planned to take a picture of "my" adaptation which in fact WORKED :) and post it -- but it will need to wait a day or two. (We have fresh snow today above the 1/8" glare ice yesterday -- we dare not venture outdoors -- to garage where I fabricated it and performed Dremeling)
Thank you all, again!
geo

PS: Re "Tech-er (CCT)" -- are you referring to Clarkson College of Technology, now, Clarkson University? If so, my older son went there -- waaaay northern N.Y. -- to get his Masters"...

[georgerkahn]

I am so happy to report all is well :)! Thanks to much needed advice -- special note here to Texas by God -- I fabricated my own "gizzy", which worked marvelously! I just took a brass hinge from a junk box, drilled a #30 and a #31 hole in it reckoning one would provide best-fit for my too-long grip screw, and from another junk jar removed a 1/4-20 bolt and nut. Folding (closing?) the hinge on my too-long grip screw, using the bolt/nut to firmly hold it (picture at left), I was able to apply very gentle pressure with a grinding disc in a Dremel -- to get the perfect length, without messing up screw's thread to make re-use an impossibility! Thanks again to all -- and, as I said I would, I've posted pictures of the device I used.
geo218773218774218775

[Texas by God]

Got r done!

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