Mostly 1911 smiths use Keller or rotary table with modified angle plate. I believe there are only two smiths use Jerry design.

 

I have a rotary table and a virgin 5x5 angle plate. I've seen people use that setup for doing horizontal cuts, but not sure I've seen a setup for doing the verticals that way. I'd assume some form of an indexing plate would be needed.

 

I have the keller and do some stuff on a rotary with fixtures .

Not exactly sure why Keefer did the dividing head other than being able to stay with one set - except moving from horizontal to vertical .

My favorite is the Pete Single thing .

Kirk

 

If you have a vertical and horizontal rotary the advancements for the vertical lines can be done in degrees. At 5,6 and 7 degree increments. 30 lpi, 25, and 20. I also use a Keller fixture however.

 

I didn't think doing the lines by the degree wheel on the rotary was very accurate? I thought an index plate with predetermined holes was the way to go for accuracy?

 

If my math is right, to cut 25lpi I would need a *17 hole plate for my rotary table (HV8 Chinese clone 90:1 ratio), which they dont appear to make, with 26 being the lowest.

However, I have overlooked something. I was thinking about the degree markings on the circumference of the table instead of the minutes and seconds markings on the crank handle itself. I actually have never used those before, being I mainly use that table for doing optics cuts. Going to take a deeper look at this later tonight.

Still learning everyday. The light bulb moments keep me interested.

*Wrong math, chart for DP-2 index plate confirmed correct math, need 93 hole plate for my table, not 17 hole. Plate B has 93 holes in the list and is available.

 

radius of the front strap after truing - turn that into diameter - turn that into circumference of a circle in inches x 25 = divisions on dividing head

360 (degrees) divided by divisions = degrees on rotary table

I think ...........

 

That's the same formula I used earlier and made sure I understood what each step was calculating and why.

 

So, I did a little test to make sure I understood the formula and what each step was telling me. This has me more excited now.

This will make some laugh, even myself a little. I found a socket that measured .812 OD. Popped that into a 13/16 collet on my mill and wrapped some tape around it. Put a pen in my machinist vise and snuggled it enough to keep it stable but still able to move it slightly. Centered that up and began making lines. The math said for 25 lpi, make a mark every 338.87 moa on the wheel, or 338 minutes and 52.2 seconds. I rounded up to 339 for testing purposes. Also, the tape made the OD slightly bigger anyways. Just wanted to see the process play out as a simple test.

Basically, I dialed 339 minutes, pushed the pen in, moved the quill up and down, pulled pen out, dialed another 339 minutes, and so on. Seems to have worked well enough by comparing to a 25lpi checkering file and other items already checkered.

This is probably the most advanced math I've used since high school almost 25 years ago. But I have a better understanding now.

 

Alls well until you decide that when you get all this dialed in and you move the y or x on your mill (depth of cut) you just wrecked all the math by changing the circumference of the cut

 

If I'm seeing correctly - I think you're ahead of all that . Looks like you can move the work piece for depth .

 

Good thing I have 20 checkering blanks coming tomorrow from Caspian. At only $5 each, I couldn't pass that up.

 

I think I'm going to move forward with this and use my rotary table for now. Found a 3/4" ball end mill with a long enough LOC to true up the front strap on the mill. Will be ordering a tailstock to match the Rotary Table and the EGW cutter/mandril combo eventually.

 

I do a mix of CNC to true the front strap and cut the horizontal lines and use the Keller fixture to run my vertical lines manually.

 

Found a couple of more ebay deals. 90 degree cutter that should give me just enough clearance for doing horizontal cuts for $30 and nice sized Harvey 8 flute 60 degree cutter with a healthy .5" reduced shank and .75" cutting head. Talked the Harvey seller down to $60.

 

Almost completed making a fixture. Just need to shape the top aluminum block and modify the rear support bracket to mount to the base plate and top of the frame support rod.

Made a fixture plate out of aluminum for my small vise, that setup mounts to my 8" rotary table. The vise has a v-jaw that clamps the upright support rod. The vise is clamped down with toe clamps.

The rod that goes through the frame is an old inner tie rod end (14mm diameter). It is very rigid already and should be rock solid after I get the rear support done. If this doesn't work out for some reason, I have a back up plan.

 

To give a little more detail.

- I put a flat edge on the back of the threaded rod, that will sit against the fix jaw in the vise, opposite the v-groove. Figured that would help stabilize it a little better.

- I also cut a flat keyway further up the rod for those bolts to contact. The bolt ends were faced on the lathe.

- The little plate that goes in the frame opposite the rod is threaded M6-1.0 for 2 allen bolts and gets pushed against the other side when the allen bolts are tightened. The nuts will get snugged up to help keep things from loosening.

- The top of the rod is threaded 1/4-20. The rear support bracket will attach there to add rigidity.

- The 14mm nut gets snugged up and puts downward pressure against the aluminum block and pistol frame. Saw another fixture like that and kept it in mind. The nut was the original tie rod jam nut and had to be reduced from a 22mm width on the flats down a small diameter and I milled flats on it to fit a 5/8 wrench.

- I used a roll pin at the base with a large washer to give the bottom support when snugging up that top nut.

I got hung up on this project forever and couldn't seem to get this section of it started, so I said screw it and just dove in, figuring it out as I go. I know it looks kinda sketchy, possibly hillbilly-ish, but oh well.

Plan B is to weld that 14mm rod to a steel base and clamp that in the vise, which would add some additional adjustability, because I could pivot that as needed within the jaws. My original plan was something like that with a one piece aluminum block and upright that was shaped like a magazine. But I got into a tail spin on that design, mainly because it wouldn't account for frame variation angles not all being 17.5 degrees exact. Other idea was a long magazine style insert that bolted to a separate block base and could pivot and then tighten down once exact.

I way overthink everything I do. And then get analysis paralysis.

 

Random pics

 

Are you concerned at all about chatter due to lack of rigidity?

 

Yes, absolutely.

I am doing what I can to make it solid. I posted a lot of pics, but didn't explain the setup very well.

If this were your setup, where would your biggest concern be? I mean, it's really solid already without the large bracket attached yet.

 

I did the same thing when making mine, over thought each process, but it still under performed.

 

Now I am rethinking my entire setup. Which is fine, I've put this off for months already, what's more time.

 

How were you intending to true the front strap? In the vertical position or horizontal?

I've only used the Keller, and have done way less frames than Steve (Integrity Arms). But when I see the frame being held by a single rod, it looks like there is no way that it won't chatter very badly, especially when trying to true the front strap up.

I would like to make my own fixture one day. You have way more "go get em' than I do and hats off to you for making your own fixture. Seriously.

It may be beneficial to go ahead and finish it if you are very close to being done, and use it on that scrap frame so you can see first hand what you're dealing with. All this talk is theoretical until the machine is running and the frame/fixture/endmill start screaming.

Me personally, I will likely end up doing what was mentioned earlier and use a modified angle plate mounted to a rotary table that can be used both horizontal and vertical. Then you mount the frame to the plate and you end up with a rock solid set up. The harder part is figuring out a way to quickly mount and locate the magwell on the angle plate/rotary table.

There have been a few guys on here who have made their own fixtures that are super slick.

Here is a more crude straight forward example of what has been suggested here:

http://dave2.freeshell.org/1911/check4/check4.htm

Good luck and keep us posted.

 

I plan on trueing the front strap in the vertical position. I am revisiting the angle plate designs amongst other things. Appreciate the replies and insight.

 

Revision #??

I had a new 5x5 angle plate sitting around and also an old parallel that had seen better days. I saw this style setup on some random site from 2010. This allows the grip screw bushings to stay installed, but also uses the one as a pivot. I drilled and tapped 3 holes 3/8-16 and added a little block for that top bushing to pivot in. Milled out the parallel as needed and made it slotted for angle adjustments. Just snugging up the bolts and it's noticeablely more rigid than my previous "rod" setup.

I still need to chop the top of the parallel off, cut off a section of the base to allow the table to rotate when in the vertical position, and also make clearance cuts on the one side of the plate to give cutting tool clearance.