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Thread: Get a grip with a 3D pantograph!

  1. #1
    Join Date
    Nov 2010
    Location
    Farmington Hills
    Posts
    133

    Default Get a grip with a 3D pantograph!

    I'm nearing the end of my first 1911 build and decided that with all the work I've put into this project I should take the time to go the extra mile and put personalized grips on it.

    I liked the look of dark colored grips with a metal medallion inlayed into them such as those from STI and Packmayr so I decided to make a pair using my family crest (Griffin) as the medallion. The grips were the easy part. I chose Kingwood for the wood because of its density and hardness, as well as its oil content. Finishing is not required with Kingwood, a simple buffing will bring the oil to the surface which makes for a durable good looking "finish". Using grips from another 1911 as patterns, I roughed them out on the band saw, drilled a counter-bored the holes and screwed them to a piece of wood to use as a handle. Then I finish shaped them on the belt sander and added all of the various clearance cuts for the ambidextrous safety, the spring plunger and the magazine release mechanism.

    I had already checkered the front strap of the frame, but doing it on wood would be a new experience. I picked up a few basic checkering tools from Midway, decided on a pattern and got to work. It was pretty uneventful but the pattern did get away from me once and I had to sand it down a bit to get it straightened out. Thankfully the grips were on the thick side so there was room. I found it challenging to keep the lines straight as they progressed across the field. Occasionally switching to the single cutter helped adjust them along the way. The kingwood checkered beautifully, even better than the scrap piece of walnut I was practicing on. The most difficult part was to keep the lines from cutting into the X shaped bead across the middle. The best way to avoid that was to finish all the checkering before adding one more row to use for the bead.

    Once the checkering was finished, it was time to tackle the medallions. Since I couldn't see myself hand engraving a Griffin into a 1/2" diameter medallion, building a pantograph was a necessity. The internet provided numerous plans and ideas that enabled me to come up with a suitable design. I built a CAD model of it first to check the operation before cutting any metal. I used aluminum for the arms with close fitting flanged brass bushings and hardened and ground stainless round for the pivots. The spindle was made with some class 5 flanged bearings I had laying around with a small DC motor for power. I was using a tiny, pointed carbide burr to do the cutting so it didn't take much of a motor to drive it. I used a set screw to hold the tool but now that I know it works, I'll probably redesign the spindle to use collets and maybe an offset belt drive motor to allow larger cutters.






    Once the pantograph was built, a pattern for the Griffin was next in line. I scoured the internet once again and came up with a nice simple drawing of a good looking Griffin and used that as a pattern to carve a 3D version out of hard maple. A 10:1 ratio was the plan, so the pattern ended up at five inches in diameter. The pantograph will also do 1:2, 1:3, 1:4 and 1:6 reductions. After doing a trial run, I decided to add a fillet around the rim which is what the green stuff is in the pictures. One part of the pantograph that is not shown in the pictures is the counter balance. When I first tried to use it, it was obvious that some sort of arm would be required to take the weight off the stylus. I just cobbled something together to do cut the medallions but plan on making a permanent counterbalance.

    With an appropriate high speed spindle, the pantograph could be used to engrave wood directly. Not sure if it would work for checkering, but it would certainly work for monograms or scroll work, although the patterns would need to be at least two or three times scale. I used 10:1 for the brass. Otherwise, the tool would tend to dig in and be hard to control.





    The medallions are brass and will be nickel plated to match the slide on the pistol. The rest of the frame will be blued. The medallions are pretty much as machined. If you follow the link below, you can get to monster sized images that show every machine mark. I touched them with some Scotch Bright while they were in the lathe, but I didn't want to do too much and risk losing detail.

    More and larger pictures are available here.

    Due to a number of requests, I have created the following PDF files which include detail drawings and an assembly drawing for the pantograph.

    Pantograph Assembly

    Rear Arm

    Bushings

    Long Side Arm

    Mounting Bracket

    Pivot Yoke

    Short Side Arm

    Spindle Arm

    Spindle Photograph

    I used close tolerance AN bolts for the pivot points that set the ratio, with nylon lock nuts and washers. If you use hardware store variety bolts, be sure to mic them and ream the holes to suit, the less play in the pivots the better because it all adds up. The pins in the Pivot Yoke and the Rear Arm are made form 1/4" ground shafting that I had on hand. McMaster Carr sells it. One improvement I would consider after using the pantograph would be to modify the mounting bracket to include adjusting slots to set the center of the horizontal pivot to the height of the work. No details of the spindle were included because I just used parts on hand to make it. It was made from small flanged ball bearings and a DC motor and uses 1/8 burrs or cutters. You could devise your own or adapt a Dremel. The stylus should be the same shape as the cutting tool you are using but proportionally larger. The aluminum construction worked fine for cutting brass but would likely be too springy to cut steel. Making the arms out of steel bar might be a better option. A counter balance of some sort needs to be added. When I was cutting the medallions for my grips I just clamped a piece of angle on the rear arm and added weight until it balanced.

    Have fun!

    Tom
    Last edited by TGriffin; 02-22-2012 at 10:08 PM.

  2. #2
    Join Date
    Nov 2001
    Location
    Toledo, Ohio
    Posts
    9,151

    Default

    Tom, nice writeup and nice job. Another example of needing a tool to do a job taken to the max. Pantographs can be useful tools to have. They do a nice job on manking firearms as well. there is nothing worse than seeing a nicely done gun with the caliber hand stamped in a crooked line on the barrel.

    Tell us more about the 1911.
    Jim H.

  3. #3
    Join Date
    Nov 2010
    Location
    Farmington Hills
    Posts
    133

    Default

    Thanks Jim.

    The 1911 is built on a Caspian Officers frame and slide. Features I added to the slide were rear cocking serrations (undercut like the original), french cuts and an EGW full length guide rod system with reverse plug and flat ISMI recoil spring to deal with the limited space available in the short slide. I also made and installed my own Novak style rear site and unique front sight with an axial dovetail instead of the traditional crosswise dovetail. This looks a lot better since most of the dovetail is hidden and what does show is mostly covered by the barrel bushing.

    There was some interference between the frame and the Storm lake bull barrel and that required some "massaging" to get the barrel to drop down far enough to clear the locking lugs. Hand checkering the front strap was probably the most challenging part of the project. It took nearly 25 hours and resulted in numerous blisters from handling all the tiny files. Since the gun is intended to be carried, I also fitted a beavertail grip safety and snag free hammer. Mild dehorning is also part of the plan for the frame and slide.

    For finishing the slide, I intend to glass bead it and then polish the slap sides before electroless nickel plating it, the grip medallions and possibly a few other parts. The frame will also be glass beaded but blued using the sodium nitrate/lye procedure. The concept of handling molten salt and lye mixtures sounds like an adventure to me!

    Tom
    Last edited by TGriffin; 02-14-2011 at 12:16 PM.

  4. #4
    Join Date
    Dec 2007
    Location
    Montezuma, IA
    Posts
    978

    Default

    Good job so far, Tom. The bluing chemicals are not molten, but are a super saturated solution with water, that should be boiling at about 292*F.

    David
    David Kaiser
    Montezuma, IA

  5. #5
    Join Date
    Jan 2006
    Location
    Northern Neck Virginia
    Posts
    496

    Default

    Another over-achiver.

    Very nicley done.
    Ignorance is curable through education.

  6. #6

    Default

    WOW! Great work!

  7. #7
    Join Date
    Jan 2009
    Location
    Dartmouth, MA
    Posts
    179

    Default

    I'd love to build this pantograph for engraving info on barrels.

    You should do a dimensioned write up with a source for supplies, especially the little DC motor..........I know I'd gladly pay a few $$ for such a document.

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