HP inset bar

[Brad]

I have a good donor mould to try making an insert bar HP. It is a 2 cav 429421 I already did some work on, things like opening up the drive bands.
Placed in my mill vise I indicated the top surface in X and Y. In X it varied by .001 across the width. In Y it varied by .0015. I have the mould oriented such that the split in the mould is in along the X axis.

I did run a mic on the bottom of each mould half. One is .684 and the other .688. Not a big deal as I will indicate off the cavities for the HP pin.

 

[KeithB]

Good start. I always thought that a small vise that could be rotated around the X and Y axis with a couple of very fine adjustment screws would be ideal for dialing in a mold. I've seen all kinds of sine bars, sine plates, and rotary tables, own several varieties of them, none of them are exactly what I have in my mind. Sigh. Maybe one day I'll sketch out what I'm thinking of.

You said it is oriented with the split line in the Y axis, so is your vise holding the mold closed? How is your vise oriented on your table? I would want my vise to hold the mold shut, i.e. split line parallel to the vise jaws.

 

[Brad]

The vise is holding the mould shut. The split line is parallel to the vise jaws.

Plan is to mill for the bar first. Make the bar and get it fit. Put bar in place and indicate top as square as possible to spindle. Find center of each cavity, center drill, and drill thru mould and bar in one pass. Remove mould from vise, rotate and locate holes for slide rods. Drill thru mould and bar.

I am tempted to drill for slide rods first but they would get in way when clamping mould in vise. Might be possible to make short rods for workholdig and replace them with permanent rods once completed.

Might get some 5/32 polished and ground O1 as it would thread 8-32 well. That would be good for slide rods.

Lots to ponder before I make any cuts.

 

[KeithB]

Measure twice, cut once...

 

[Brad]

Might even measure 5 or 6 times. Easy to remove more, hard to put it back.

 

[KeithB]

If you do decide to put in the cross pins before you drill the HP hole put the side that does not have the pins up against the fixed side of the vise. You can cut a little piece of scrap narrow enough to fit between the pins and long enough to touch the moveable jaw of the vise before the ends of the pins do. I think the cross pins in mine are a slight press fit so they stayed in place in the inset bar while I was drilling.

 

[358156 hp]

 

[Wasalmonslayer]

Watching closely

 

[freebullet]

Geez, the next day, no pix, no update... Brad ya alright?

Hope he didn't brush some chips away with his finger in the mill bit.

 

[wquiles]

Cool project. I would love to see pictures

 

[Brad]

Geez, the next day, no pix, no update... Brad ya alright?

Hope he didn't brush some chips away with his finger in the mill bit.

Got up and drive to Lincoln for the first show.

Got to meet up with Bob for a bit, see an old friend we haven’t seen in better than a decade, and bought a single 1911 mag with GI tapered feed lips for 15 bucks.

Passed on a few decent deals but not stuff I needed. A nice Savage 340 in 222 Rem for 360.

 

[Brad]

Base is pretty square top. I am actually pretty shocked.
Got some measuring done to see how long, wide, and tall I want the bar. I need to look at desired HP size and how to get the HP and slide pins where I want them.

 

[Brad]

Got the pocket for the bar milled.
I started by finding center then used a 1/4” drill to remove much of the material. These holes were drilled .25 deep to leave material for finish passes to get a flat bottom pocket.

I then used a 1/4” end mill to remove the web between the holes and remove most of the excess material on the sides.
Final cuts were made with a 3/8” end mill to final length and .375 deep.

 

[Will]

Good job Brad

Looking forward to seeing how this works out. Probably makes you wonder how Hollow point molds is able to do it so cheap.

 

[Ian]

Not tea-bag there Brad.

 

[freebullet]

Real nice work, Brad.

Any thoughts on threading the bar pins (like mp comes) or are you thinking of a press in like Keith was sayin?

Just thinking from my inexperienced pov, would seem threading them & leaving them slightly loose may workout better if the alignment wasn't as perfect as hoped for.

 

[Brad]

I will probably do like Keith did but in reverse. I will put the HP pins in place and then drill and tap for the cross slide pins and drill and tap them in place. That locks the HP pins in place.
I need to decide how large the cross pins need to be. I have some measuring to do.

 

[Pistolero]

I was mulling this very thing over the other day, and came to the same conclusion as you
did Brad, that putting the inset bar in place and THEN drilling the HP pins thru the mold and the bar
all at the same time was the only way to get it really right. And once the HP pins are there locating
the bar accurately, the slide pins should be pretty straightforward, since they don't actually have to
be anywhere special, just parallel to each other and perpendicular to the HP pins, which is pretty automatic
in the mill, of the outside of the blocks is square......if, assume, pray.

Bill

 

[wquiles]

Wow, nice work Brad. Looking forward to future updates

 

[Brad]

Just placed an order for some drill rod, a die, and a couple taps. While I wait for that to get here I will make the inset bar and drill for the HP pins and get the pins made.