I have a part being machined that calls for 2 captive studs to be inserted and thought I'd try to put the studs in myself. They're stainless, 8/32 about an inch long and require a .163 pocket (partially drilled hole).
I thought that maybe I could build some sort of jig to keep them straight and then tap them with a hammer?
Is there a small accessory or something that maybe I could use with an arbor or vise? Any ideas?
Need to do them myself to save some time and money.
Not sure this is the same stud, but it probably is similar to some I have used. I took a piece of steel and drilled a hole that would barely clear the threads. I faced it on the lathe so it was flat and at a right angle. I place the material with the stud in it on a flat surface, stud sticking up through the material, and place my driver down over the stud. I then whack it with a hammer until the stud is flush on the back side. This was done to put 4-40 studs in aluminum sheet, and worked quite well.
If you're using the stud I think you are, the hole diameter is pretty important. It should have a shoulder that is knurled, and below that, a circular dovetail-like feature. The shoulder cold forms material into this dovetail for pull out resistance, while the knurl keeps it from rotating. If the hole is even a few thou too big, the stud won't hold securely. You want the smaller diameter to -just- fit the hole.
They also take a fair bit of pressure, even for a #8. But a length of
1/2" CRS faced square, with a center hole just big enough to take the stud, is the tool you need. An arbor press will be needed, or if the holes are close enough to the edge, you can use a vise. I've done plenty of PEM inserts with my Kurt vise.
Hammering directly on the stud doesn't consistently work well unless you have unusually good aim and control. You could hammer on a smooth- faced steel block placed over them. As mentioned an arbor press or milling vise is better. You can pull them in part way with a nut to keep them from shifting in the press fixture.
The common fixture is a drilled steel block attached to the arbor press ram.
**Something similar I do: ** I set alignment pins in molds now by drilling the press fit and the slip fit in both plates and using the slip fit side as a guide for starting the pin. Then I just smack it with a hammer to start the pin. (Usually 18-8 into
6061) Since I cut the molds on the little CNC mill I usually cut a short pilot hole and chamfer before throwing them on the drill press, but I could drill and chamfer on the mill quickly enough if I had a different machine with a tool changer. For me its faster and accurate enough to hand drill (on the press) those features.
** A possible solution for what you do: ** I think for a threaded stud (I assume half threaded and half press fit from your description) I might make a thread on bushing for the threaded half. Then drill a hole in a piece of plate that is a nice slip fit for the outer surface of the thread on bushing. Make the bushing longer than the thickness of the plate. Use a plate substantially thicker than the press fit portion of the stud. Chamfer the edges of the press fit hole in the work piece to assure proper starting of the stud, also to prevent ridging around the pin. Smack, press, or clamp as needed. When the face of the bushing meets the work piece remove your guide plate, and unthread the bushing.
** Comments: ** It's a pretty simple concept, but if you like I'll make you a quick sketch. Refine of course for desired level of precision and accuracy. Variations on the theme could be used for a stud that is only partially threaded on the exposed end etc.
If you have multiple studs you might make your guide plate as a template for all of them instead of just one at a time. Obviously not practical for multiple studs going into planes at different angles or surfaces at different levels. Possible though if production numbers are high enough to justify a special jig.
For a little ease of removal cut a bolt head on your drive bushing. For work piece protection if necessary pad work piece face with leather or rubber. Glue to drive bushing maybe? Maybe machine an acetal or HDPE bushing for the work piece face of the drive bushing?
By drilling and threading your drive bushing all the way through you might be able to use a set screw from the drive end (hammer side) to set and/or adjust your drive depth easily.
Not turning at all. You can make a tool to put in the chuck that fits the stud, or if you only have a few to do, you can thread a spacer onto the stud to protect it. I used a simple tool - a piece of round stock with a clearance hole for the stud drilled into the center.
For pressing in threaded inserts, I just used a hex bolt chucked in the drill.