Love those analog readouts (with apologies to PatMarlin)

[theperfessor]

Did this a while back, just got around to taking pictures. I use my 7" South Bend shaper to cut vent lines on the inside faces of my bullet molds. The horizontal lines are put in at .1" spacing, while the vertical lines are on .6" spacing to place them between the cavities. My shaper has a 10 TPI lead screw on the cross feed axis and a 0 - 100 collar. I have no trouble with the .1" lines as I just turn the screw one full rev, but the last time I cut the .6" lines I miscounted one rev and ended up screwing up some mold blocks.

I ordered a 18" steel scale with one axis marked in 1/10" increments. I cut off the scale to 14", put a 1/4" wide by 1-1/4" long slot in each and, and made a couple of little brackets from some scrap aluminum to clamp it to the cross travel axis. Another piece of scrap turned into a pointer that I bolted onto the side of the table.

Now I can just line up the tool with the edge of the block, move the scale until one of the scale markings lines up with the pointer, and go from there. For the .6" lines I use a felt tip pen to mark each increment (it wipes off with a little acetone), and just move the table from increment to increment, always returning the 0-100 dial to the same spot. Perfect! No more mis-spaced cuts.

The title is a tribute to my friend PatMarlin, who is very innovative in his use of digital readouts.

[elk hunter]

Perfessor,

Interesting and very practical idea.

When I replaced my two 9 x 42 mills, both had DRO's, with one 10 x 54 I didn't get a working DRO with it. I intended to order one, but just didn't get around to it. You know, I really haven't missed it all that much. It does force me think ahead a bit, but that isn't all bad.

Love your SB shaper. I'd like to find one, but they're about as rare as an honest politician here. I'm making do with a WW-2 Porter Cable.

[PatMarlin]

Very cool perfessor. No stinkin' batteries needed.

Quite frankly, I'm dissapointed with the Harbor Freight dro I put on my manual Hardinge. It drifts and is junk,. Meanwhile I'm getting quite attached to the large wheel and standard rulers on the machine.

The old style (HF black face) DRO's on my Logan are stable and still work very well. I think there's been a few cargo containers chucked full of digital calipers from China that are Junk. The silver faced ones- as I read other complaints on the net. Every pair I've tried was junk, so I finally bought Mitutoyo.

[theperfessor]

I put a caliper-type DRO on the quill of my 10 x 54 vertical mill last summer. I like it but to be honest if it ever breaks I'm going to replace it with a dial caliper modified to fit the bases similar to what you do with digital calipers. I like the continuous reading aspect instead of waiting for the display to refresh. And yeah, no batteries.

I really love the DRO I had put on my lathe. It has changed the way I think about setting up and running things. Wouldn't want to go back to not having one on it. Some of the best money I ever spent on equipment.

If I ever need to cut anything close on my shaper I'll use a dial indicator. My main problem was being .1" off, not being .001" off. Screw up a couple of mold blocks and you start wondering what you can do to prevent mistakes such as that again.

[arjacobson]

A dro on a lathe would be nice!! I learned years ago to ake up the back lash and always go that way on the dial.. Did many one off bolt hole circles that way but a dro would have helped out a BUNCH... Many of the older tool room guys used to run boring mills with jo blocks and tenth indicators..They could do some serious accurate work!!!!

[PatMarlin]

Mechanical dials are fine if your machine has no backlash obviously. My Logan has way to much for the dials.

Travadials are real nice. I have those on my mill.

[arjacobson]

Pat every manual machine should have a bit of backlash.. You just have to make sure you are always doing your moves one way only. My bridgeport has .012 backlash. If I indicate the end of a pc with the backlash taken out and zero the dials I can make accurate moves all day long. If I have to go the other way I go past zero and then come back..follow me or am I making no sense at all??LOL

[Tazman1602]

Hey Perf,

Neat idea............don't have any pics of your molds once you have made all the cuts do you? Just curious, I've had to vent several Lee molds to make them work properly but have always used my carbide checkering tool.

Art

[theperfessor]

I used to run a very large Gray horizontal boring mill with a 6" spindle. The bedways and the vertical column had a vernier scale buried in them. Once you zeroed in on a location you had to read the current location of the vernier scales and then manually add/subtract the distance you wanted to move to the "home" coordinate to get your new reading. The machine had about eight feet of vertical travel and twelve+ feet of horizontal travel. One job I remember was a very large ring gear that had 48 holes in it. I was one tired puppy after climbing up and down from the work platform to get down on my knees to read the horizontal vernier scale for every hole.

Taking the slack out the same direction each time is good practice, and a machine with little wear can be positioned very accurately with just the dials. The long term problem is that the axis screws will wear unevenly, just as the guideways will. It's always where most of the work is done, usually the middle of the travel of a vertical mill and near the headstock of a lathe. Theoretically the readout should be less likely to show positioning errors due to wear than the lead screw.

The type of have on my lathe has no glass scales or gear drives and all the moving elements are well sealed. It uses steel balls sealed in aluminum tubes that are fixed in place to the axes. The reader is a set of magnetic coils in a sealed aluminum block that simply slides over the tube. Oil-proof and chip-proof, everything is all sealed up.

[PatMarlin]

If I have to go the other way I go past zero and then come back..follow me or am I making no sense at all??LOL

I understand perfectly. You have to rewind and start again ...:mrgreen:

It's not a problem unless you're trying to do some production work, then in becomes a pain. My manual Hardinge chucker has some backlash, but when you go one way with it, it gives you increments of .0005 on the big wheel dial that is dead nuts.

Amazing machine, specially compared to my Logan.

[theperfessor]

Tazman, check these pics out. The horizontal lines start .1" below the top surface and are spaced at .1" intervals. My molds put the bullets on .6" centers and .6" from the end cavity centers to the ends of the blocks. The molds in the picture are 3.6" long. The first line is .9 " from the end and then every .6" apart from there. I can make 1 to 5 cavity molds with my existing tooling and fixtures so having a modular design where every cavity adds a fixed length to a mold simplifies a lot of things.

I only cut vent lines one one side of the mold set. I use a standard 60* threading tool with a sharp point and go about .006" deep. I'm using the molds in the pictures to work on another project and have cast hundreds of slugs at a variety of temperatures with several different alloys and have gotten good fill out with no finning. Haven't tried any molds yet with out vent lines or with different spacing or profile so I don't know if they are necessary or not. I know with my shaper and the fixtures I've built for it I can vent one block face in about six minutes total time. I ran 12 of them a while back and it took about an hour and a half to set up the fixture and tool and cut the dozen in one direction (vertical) and then change fixture and run the other lines (horizontal).

But in my haste I made some spacing errors - thus my analog readout. Note that in the left hand picture the second, fourth, and sixth lines are mis-spaced. Once you miscount one spacing all the rest are off. Now I just line the tool up with the edge of the block, read the number on the 0-100 screw collar, and move the scale until any of the .1" marks on the scale line up with the index line on the table. Then I use a felt tip marker to mark each appropriate increment. When I move I always feed the table in the same direction and just line up the screw collar number when the index line on the table is on the marked .1" scale increment. I can easily get it to position within +/-.003", which is plenty close enough for what I am doing. I just don't want to miss it by .1"!

Edit: The main body diameter (not the collar, that was put in there to have a feature to check for proper fillout), from left to right, is approximately 7/16", 3/8", 5/16", 1/4", and 1/2". This covers the .25 to .50 caliber range. These are made for an ongoing mold size-bullet size test I am working on.