Making Horizontal Tombstones; material preference?

Kitamura H400 (1998)

The machine came with tombstones (yay), but they are simply too big, at 10" per face.

The only problem with this machine is that you are limited in the swing you can put on B.

While a 10" face is fine for mounting fixtures to, it doesn't allow me to put on vises. I would clear the pallet change door by about 1/2" with a vise on each side. Put anything in the jaws and boom.


So I want to make new tombstones. We picked up some used pallets off of ebay for pretty cheap (450$ each), but tombstones that size are hard to come by. 400mm pallet with 6" column, 22-24" total height. I plan on mounting 4 BL6 Chick vises (6 inch vises) to each tombstone.

So, looked at material options. all options are roughly 1000$ material for 2 tombstones (base and column):


6 1/4" 6061
6.030" Durabar milled
6 1/4" Durabar cast


Originally I wanted to get steel, so I could bolt the column to the base and have it welded after, but I don't see 6"+ square readily available...


So my pros and cons for aluminum:

+weldable
+lightweight
+easy to machine

-softer
-lightweight (won't dampen as well, less mass)
-easier to strip out holes
-worse for bolting something direct to the face



For cast iron:

+heavier (dampening)

-can't weld it (can braze it though?




I honestly think the iron would be better, but worry about loosening up over time (I would dowel it and put a bunch of bolts in the bottom though). I don't like the aluminum but I could bolt it and weld it and it won't be a problem in that regard.

I will have about 600lbs+ of vises on it...

What do you think?

I'm a bit cornfused here (I cornfuse easily)

You need material 6" thick ?

By how long ?

FWIW I did a base of a fixture from 9" solid, it was formerly welded from
machined parts, annealed, and machined.

Local steel supplier had it in stock, and burned it right out
9" thick x 24" x 36" or so.

digger doug said:

I'm a bit cornfused here (I cornfuse easily)

You need material 6" thick ?

By how long ?

FWIW I did a base of a fixture from 9" solid, it was formerly welded from
machined parts, annealed, and machined.

Local steel supplier had it in stock, and burned it right out
9" thick x 24" x 36" or so.

Click to expand...

My corn fuses easily too.

I want 6"x6" square tombstones, 24" tall. Materials I listed were square. 1 vise per side.


Kurt actually makes one, but its 26" tall and about 2000$ each. Would hate to have to cut 2" off the top of brand new 'stones

So could you ask the local steel yard to burn you a piece of 6" thick material
6" wide x 24" long ?

I would guess to add 1/4" on a side for guaranteed clean up.

6 x 6 x ..... 24?



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Think Snow Eh!
Ox

Ox said:

6 x 6 x ..... 24?



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Think Snow Eh!
Ox

Click to expand...

I am not crazy, I swear!

Cast Iron, 4 face, 4 mm Base

Kurt thought it would be good to make one 26" tall

Ox said:

6 x 6 x ..... 24?



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Think Snow Eh!
Ox

Click to expand...

Them's the one you see in the cemetery that keep tippin' over....

narrow and tall tends to vibrate easy

I looked at the linked,

I don't like the mingling of metric and inch dimensions.

If the drawing is to scale, the thing isn't 6" wide looking with a 15.74 wide base.

Do you really need 24" high ?

If not, I would look into welded construction, with some diaphragms inside.

(and a couple of other tricks up my sleeve I won't won't provide here
to help in the vibration department)

I built a cpl of them that are around 30" tall, but they are prolly ... 15" octagonally and weigh a bunch, and those look tall and skinny!

I built these out of 1018 and bolted to ground A36 plate top/bottom.
Welded, normalized, and had them re-blancharded after normalize.



I wouldn't be lookin' to doo any heavy work above the 12" line on that (Kurt) sucker!
I'm sure i'd be fine for drill/tap werk in alum, but not milling much 4140 tho...


Will a little "400" even clear 26"?




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Think Snow Eh!
Ox

I made a 36" long one out of 1" x 6" CRS, each side overlaps the other and are bolted and pinned. Rigid as hell and it doesn't weigh half a ton.

I'm a little confused, though. Is this a "Horizontal" tombstone, or a tombstone for a "Horizontal"?

Larry Dickman said:

I'm a little confused, though. Is this a "Horizontal" tombstone, or a tombstone for a "Horizontal"?

Click to expand...

Yours (and maybe the Kurt unit linked) sound like A axis units used on a vertical and between centers.

I ass_ume an H400 to be an HMC - so "free-standing" unit. (and he mentions a "B")


A vert with "400" in the name would run out of X long before reaching either end of a 26" long stone?


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Think Snow Eh!
Ox

yeah, its a horizontal machine

the clearance between the pallet and the tool change door (which is above the spindle) is 25.5", so 24" would be good. I could do fine with 20" above the tombstone "flange", as the vises I will use are about 19.5" long

The Kitamura H400 lists @ only 20.1" in Y.

I guess we don't know Y0 ref to top of pallet...
I would ass_u_me near flush?


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Think Snow Eh!
Ox

That'll teach me to read the title.

I would go with a one piece cast iron one then. $2K isn't bad.

dandrummerman21 said:

yeah, its a horizontal machine

the clearance between the pallet and the tool change door (which is above the spindle) is 25.5", so 24" would be good. I could do fine with 20" above the tombstone "flange", as the vises I will use are about 19.5" long

Click to expand...

I spose if you just have handles up yonder - it should work OK eh? (not really using (thrusting on) the top portion)


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Think Snow Eh!
Ox

Bolt the vises vertically, directly to the base plate. Make steel risers if required.

Then make a 6x6 aluminum stiffening beam that spans nearly the length of the vises, and bolt all four vises to the stiffener. The stiffening beam does not need to be bolted to the base plate.

Ox said:

I spose if you just have handles up yonder - it should work OK eh? (not really using (thrusting on) the top portion)


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Think Snow Eh!
Ox

Click to expand...

Yeah, I have 20.2" of y travel, goes up to 22.25" above the table. I'd be cutting mostly in the 6-15" range above the table. I don't anticipate doing anything too heavy on this machine. She is built for it, box ways and 15hp spindle. I will take a heavy cut from time to time, but would rarely do more than 50% spindle load. Not pushing 2" drills through anything, 1" spade through 4140 is the most I might do.

Orange Vise said:

Bolt the vises vertically, directly to the base plate. Make steel risers if required.

Then make a 6x6 aluminum stiffening beam that spans nearly the length of the vises, and bolt all four vises to the stiffener. The stiffening beam does not need to be bolted to the base plate.

Click to expand...

That's an interesting idea. I might run with that, or maybe modify the idea somewhat. The vises do have bolt holes in the back. I'm just a bit worried about making the whole thing square once bolted together. The back face holes are just plain tapped holes.

The vises have 1/2 dowels on the backs, I would like them pinned together. I was more thinking that I would bolt the square to the pallet base, drill and tap and ream holes for the vises, then put ground blocks or jack screws under the vises so they are making contact with the base too. So I don't think it would be as flimsy as it was made to seem above.


I think I'm going with the cast iron. I was just looking for some aluminum fans to tell me how much greater aluminum would be.

dandrummerman21 said:

I think I'm going with the cast iron. I was just looking for some aluminum fans to tell me how much greater aluminum would be.

Click to expand...

I read somewhere that epoxy granite is good for c and c's.