Cherrys

[Greg5278]

I am in Central New Jersey. The blocks won't cost much to ship in a flat rate USPS box. They could be sent for $7.70. I was going to cut the blocks with precision edges on the mill, and saw one edge. I wasn't going to do any other machining, but it would be clean pieces ready to finish with holes, etc. The grade will be 65-45-12 cast iron, and be annealed, there won't be any sand or scale on it, because it is continous cast. Greg

[trk]

Having a mill, I'm intersted in the basic blocks. Not having a cut off saw, having the rough cut blocks rather than a bar would be good. For 7.70 you can ship more than the box will handle (I've shipped 56 lb of rounds and DOM ends). When we get magnets shipped in, there is 14ga metal wrapped around them to keep the contents together. Obviously I'm interested. Which iron do you specify? It may be that through a local machine shop (that gets good rates because of high volume) that I could get us a good price.

[trk]

44man -

Did you make your own left-right threaded rod and nuts or did you purchase them. If they're available I'd much sooner purchase - especially if I could get something hardened and ground. Vee or acme threads?

[Willbird]

I'm assuming the squeeze maker consists of a single lead screw with lefthand threads on one end and right hand on the other end.

for what it does it could be made good enough on a simple lathe.


Bill

[trk]

I'm assuming the squeeze maker consists of a single lead screw with lefthand threads on one end and right hand on the other end.

for what it does it could be made good enough on a simple lathe.


Bill

Both assumptions are correct.

BUT I'd prefer fto find something that is more precise and hardened (preferably ground) to withstand wear. I learned long ago in industry, if you can buy it do so - it will be much cheaper and as a production item will be better made. I have found L-R threaded studs in McMaster-Carr, but they are relatively short and only made of 1018 (cold rolled) steel.

And, since it's been 1968 since I've cut threads on a lathe, I'd just as soon not take the time to teach myself how to do it at this time.

[44man]

I cut the threads on the tool steel shaft with the lathe. I bought a left hand tap from E taps, real cheap, to thread the block. There was some difference but some lapping compound made everything fit. The threads are 7/16". No nuts are needed because the blocks are threaded.

[Buckshot]

.............If you're looking for ACME threaded rod you can get it in various accuracies from Nook Industries, or Roton plus another which escapes me at the moment. You can get it in low carbon 1018, 4140, and a couple grades of stainless. These places also supply nuts in plastic, bronze and cast iron. These ACME rods can be ground thread, rolled or cut and are usually priced by the foot.

What 44man has made, and very nicely done too, is a double acting or self centering vise. You can buy these from Kurt with 4" and 6" wide jaws. They quote accuracy over the entire jaw movement as .0006" and .0002" repeatability. They're angleloc's so the tighter you tighten them the harder they pull down. You can also 'set center' where you like within a range between the 2 closing sets of jaws.

Since Kurt vises of this size and single acting go for a $400 - $600 I would imagine these specialty items might be half again as much. But then maybe not.

...............Buckshot

[44man]

It would be nice to buy something, but remember that I am retired and even have to sell guns to buy a new one. My labor is free for me and the low cost of my materials makes it much more enjoyable. I would rather make something from nothing then spend money I will never recover. Besides, it is more fun.
Since the blocks are threaded for the screw, how could you thread them with Acme threads? I have no way to lathe cut them and don't know of any taps. Hard to tap them things anyway. You would have to fasten a nut on the end of each block.

[Greg5278]

The blocks are of 65-45-12 cast Iron. They were priced through my Grandfather's machine shop. No discount is available from Durabar metals. Their product is continous cast, and free of scale, and inclusions. They guarantee the product, and supposedly make the best USA made cast iron.

The price would be reasonable for the blocks. I will add a little bit in for my machining time on the mill, and the cutters. But it will still be better than buying blank blocks from RCBS for $90. The holes will be up to you. I can cut the slots for the RCBS handles at .305-.310". I am probably going to cut the handle trough in 12 inch strips of material. My last set of mold blocks were 2.000" high by 2.000"wide, and 1.875" long. I guess I could do 2 inch cubes, but then I would waste more material. Let me know what you might need.

[Buckshot]

..............44man, believe me that I completely understand what you're saying when yo'd prefer to make it yourself. Since you already had a setup my post was more directed at someone else who might not have the materials and means to do what you did.

However, to answer your question about the ACME thread and your existing blocks. The grey castiron nuts sold for the ACME threaded rod are round, not hex shaped. They're intended to be machined to a shape to suit, or to have a flat milled in them.

In your situation I would clamp your jaws together and then bore through to a suitable diameter (maybe turning the nuts too) to accept the nuts. The nuts would then be fitted to the bores in the jaws, locktighted and pinned or fixed with setscrews.

...............Buckshot

[44man]

Buckshot, I get you now! They would be nicer then regular threads. I might convert in the future. Thanks for the info.

[Buckshot]

Buckshot, I get you now! They would be nicer then regular threads. I might convert in the future. Thanks for the info.

.............Well I don't know about 'nicer' but they'll sure stand alot more pressure on them then standard 'V' threads in cast iron. Another nice thing is that when the time comes that the ACME rod starts to show some wear (or the nuts) , you can remove the ACME nuts, slit them across their axis through the threads and then drill and tap a hole in one side and install a setscrew.

Tightening this down will spread the nut a tiny bit and remove any backlash. My lathe's cross slide screw was a bit worn in the middle where most all the motion takes place and I did that. The only problem is that now when you move the cross slide beyond the centerline it gets a bit harder to turn on the unworn section. But, I don't often get back there.

I did order a 5/8-10 lefthand ACME screw (accuracy .001"/ft) from Roton and 3 nuts so I can eventually replace the 7/16-10 factory screw. The nuts are for the existing cross slide and then 2 dual toolpost cross slides I have. That 5/8" diameter screw shouldn't show any wear until well into my grandkid's use of it!

................Buckshot

[Willbird]

I can find a way to DO anything hehe, thats one of my strong points.

You could buy 2 pieces of ACME threaded rod, one left and the other right hand thread, and turn one down, and drill and ream a hole in the other one, and then silver solder them together. Or use a roll pin, taper pin, or dowel pin. you Might even be able to make it a threaded joint, say 1/2-20 and use some of the super duper red loctite that is rated as strong as well applied soft solder.

I would take part in a group buy on the ACME rod with (5) other guys so we each ended up with 6" each of R and L threads.

One benefit of ACME is it seems to allow some self alingment, IE it can be sloppy axially but not be so in a linear fashion.

one can also use TWO acme nuts with a method of linear adj between them to remove backlash. if this device was closed against a strong die spring tho backlash would not be an issue ever.

Bill

[carpetman]

I read all this stuff about machining and can remotely follow some of it. What are Acme threads? I know from watching Road Runner cartoons that Acme makes good stuff---Wiley uses it frequently. I also know that there is no connection to them and Acme boots as they aren't so good.

[StarMetal]

Ray...great post...you really got me chuckling on that one as the Roadrunner has always been my favorite cartoon. You're right about Acme making good stuff and I might add in every area too. You won't find Acme products at Lowes or Home Depot tho...they are strictly mailorder.

Joe

[Greg5278]

What did you guys think of the rotary table idea on the mill to bore the molds? A boring head could be used , and save the trouble of making the doulle acting vice. I thought the best point was the cutter could be used for other bullet diameters. Did anybody want some cast iron for Blocks? With or without handle slots? Greg

[Willbird]

I read your post about the boring head, and the rotary table, I mentioned the rotary table part myself further up the thread, I would not even use a boring head, if you were going to mfg. a single flute mill cutter (which is what you would end up with) you could simply hold it in an R-8 collet. In any setup the shorter it can be with the least number of connections ends up more rigid.

What would be nice is to have power feew on the rotary table, that can be jury rigged up for a trial run and I intend to do so. The 4 jaw chuck I do not think would work very well for indexing the block to the next cavity. I myself thing a magnetic chuck on the rotary table however with a fixed "fence" to slide the block along and then some blocking around it would probably work very well. One could add a couple holes for bolts to hold the blocks closed while machining them.

the difficulty of making a series of cavities exactly the same size and depth on that kind of setup increases exponentially. if making one cavity is X, 2 cavities is X squared, 3 cavities is X cubed, 4 cavities is X to the 4th power.

The Cherry is more likely to do the same thing every time because it is more free cutting, if you can control depth you will pretty much get cavities that are identical twins, or triplets, etc.

IMHO the reason Veral (LBT) can match his cavities is that with a tracer lathe he can easily run the same profile over and over with a very free cutting tool, I would guess he uses gage pins on the rear section of the cavity and re-runs the cavity until the pin jusssssst starts, if you have .001" and .0005" pins in plus and minus tolerance you can check a hole size almost to the .0001" with practice. also with the boring process he has unlimited access to the cavity to measure it without disturbing the tool position. And he is extremely careful about setting up each cavity to get the blocks centered.

Bill

[Greg5278]

I agree with using a simple single flute arrrangement to aid rigidity. Couldn't you use the crossfeed on the table to index the second cavity. On a Bridgeport mill you can put the royary table on the normal table, and retain the normal X and Y feeds. I was told that the 4 jaw chuck is the best way to clamp molds for boring, to ensure precision. Greg

[Buckshot]

.............A 4 jaw chuck (this is my opinion) isn't the best way to hold a set of blocks. It's adequet and it pretty much works, usually. I believe the best way is in a purpose made fixture. In a fixture you can have a non moving clamp face to indicate zero off of, and thereby everything else. This assuming you're lathe boring and not closing both blocks on a cherry.

Hoch makes a big deal out of using a 2nd Operation Hardinge lathe "Specially set up to do moulds". A Hardinge is a nice lathe, and no doubt about it, but I think his mentioning it is a bit of 'dazzle'. You're working right there at the spindle nose where you have the most rigidity and accuracy. Heck, my 23 year old Logan will hold .0005" at a foot from the spindle and a tenths test indicator won't flicker running on the spindle nose. His special setup is similar to what Lee uses. A dedicated fixture plate.

..............Buckshot

[Willbird]

If we are rotating the mould on the rotary table while circlemilling the cavity, then moving the cross slide either X or Y will make the hole larger. We most move a differant portion of the block to the cl of the rotary table to index for another cavity.

for milling IMHO a six jaw chuck is the best, of the adjust tru variety, they hold a part more firmly against the loads placed upon a part by milling, one can also remove one jaw where a keyway or flat, or portion of the part is, or even two opposing jaws in extreme cases.

Bill