Pins vs Square keys

During the whole time they were cutting their gear box and since I have been roughing blanks manually in the back on the South Bend 10x54. It really has improved my manual skills for quick work, but my time is better spent letting the Tormach do rote work like that wile I work on other stuff. I also have some stock mold designs optimized for cutting on the Tormach with it 5120RPM spindle. I need to cut some of those too.

I rough to length on the manual mill anyway, but I was fully prepping hinged blanks in the back. That is time consuming.

Well, I decided to try pins. One vise is already drilled and reamed. I Figured there were two benefits to going with pins. There is more room to relocate them if I don't like the position, and they really won't interfer very much with changing to square keys if I decide pins aren't working out.

Okay... I plan to use green Loctite, so moving them will require heat, but other than that. I don't want them vibrating out since there is nothing holding them in except a light interference fit

My Microcentric pie jaw lathe chuck uses pairs of 1/8" dowel pins to locate the top jaws, with one clamping screw between them. Kinematically they should be as good as the machining of the tee slots, which you could check for tight or loose spots with an adjustable parallel. You aren't roughing out iron castings which might shift a vise secured to the oily table only by bolt tension.

The RF-31 that replaced a worn-out drill press for the company had tee slots that weren't quite parallel to table travel, and the large drill press vise (18 vs 80 Lbs) I ordered for it had no slot underneath. I milled a close fitted key at home and found with it that the table slot had loose and tight places, which I filed to an even slight drag all over.

The quill on the RF-31 shifted when clamped, limiting it to ~0.005" vertical adjustment. The Clausing can do 0.0005".

To align the vise jaws and X axis I clamped the key in its tee slot and milled the top slightly narrower, thus parallel to table travel, closed the vise on it upside down and milled the matching press-fit slot in the bottom.

I set the ram position to make the largest collet-sized endmill slightly clear behind the rear vise jaw with the table fully forward. Thus the work can be lifted out or the table moved rapidly.

These are going on a CNC mill, so a rapid to full Z height or any other safe clearance area is as fast as I can turn the MPG, or already done when I walk up if I add it to the end of the program, which I do. The M30 macro at the end of every program does a G53 to Z zero at full speed, along with a redundant spindle off and coolant off command.

I was getting a little cocky. Everything was just working the last few days. Turning parts, machining. CNC programs. Just working. The first of the two vises went perfectly. On the second one I hit hard spots and ruined the tip on every screw machine length split point letter D drill in the shop except those in tool holders on CNC machines. Its one of those I buy in multiples because it gets used all the time. I didn't want to drill the pin hole with a hand grind, because I wanted better accuracy than MY hand grinds can give you. I have two empty holes in the second vise because of "problems." Finally I ran across a .248 reamer I forgot I own. I broke the surface and cleaned up the hole by pecking donw 1/8 inch with an end mill, then I spotted with a center drill, and then I drilled it with a.242 (letter C) drill. From what I was reading .007 was to much maybe for an HSS .249 reamer so I risked the .248 reamer. finished with the .249 reamer, and set the pin.

After the first vise went so easily the second one nearly whooped me. Now to order a box of new split point letter D drills. LOL.

P.S. I had an RF-30 a long time ago. (Might have been a 31, I don't recall.) It was capable of making parts, but it was as you noted not top tier. I ran it for a while with a Kwik 200 master holder in the R8 spindle, but ultimately I decided that wasn't enough faster than the regular R8 tooling to justify the loss of clearance. I sold it to a guy who wanted it to machine lower receivers. It should be good enough for that. They have a lot of tolerance. As long as the pin holes are close to the right size and line up from one side to the other they generally work. When he showed up to buy it the darn thing wouldn't turn on, so I made him a deal on it. First trouble I ever had with it. LOL.

I made a tool that locks in a 1/2" hole by screwing in a 1/4-28 bolt but it may not scale down in length and be too much work for your welding table pins.

It's a puller for a 1/2" bronze bushing in a blind hole in the end plate of a hydraulic pump. The working part is a sleeve with a raised rim on the end that catches the bushing. Lengthwise slits ending in drilled holes let it compress to fit in. The area of the holes was bored larger than 1/4" to flex, by cut and try to balance strength and stiffness; the first try was too weak.

The area beyond the holes was tapped 1/4-28 with a taper tap run only deep enough that the fingers expand to grip the bushing when the bolt passes through. This was too fussy for multiple parts, leaving the OD large and turning it down to an interference fit in the hole with the bolt in place might be easier. A smaller stub on the end compressed in a collet would remove thread clearance and hold the split fingers securely.

The bolt extracts the bushing. The end of the bolt was also tapered to start in the compressed threads. I didn't spring temper it and multiple cycles might have cracked it.

It was a lot of work to save a bushing I could have drilled out and wouldn't reinstall if I could successfully fit a new one, though it avoided risk to the end plate. Its most valuable use has been as a pocketable example of my custom tool making ability at job interviews.

Think holdfast. Typically pins and blocks just work as workstops.

A common welding table hold down clamp, just looks like a bar clamp. Remove the fixed jaw and weld a round stub. On the end of the bar.

Think holdfast. Typically pins and blocks just work as workstops.

A common welding table hold down clamp, just looks like a bar clamp. Remove the fixed jaw and weld a round stub. On the end of the bar.

-- Bob La Londe CNC Molds N Stuff

-------------------------------------- I replaced the plastic stops on my B&D Workmate with dowels stepped to fit the holes, and they make good clamps. My welding table is a damaged street drain grate with openings large enough to insert the whole bar clamp.