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spongerich
09-29-2015, 11:52 AM
I have a Clausing 8520 milling machine and I would like to fabricate a 4-5" tall riser block for it to gain some more space under the spindle.

I have a main body casting from an old Atlas horizontal milling machine that's the right width, but it's about 14" long, so I'd need to cut out a section to make a square tube out of it.

My welding equipment is limited to a Lincoln tombstone and a tiny Oxy-Map torch. I do have a shop oven that I could use to pre-heat the parts up to about 600 deg.

Is this something best left to a welding shop? I could machine and prep everything first.

What about non-welded solutions? I was considering drilling and tapping a series of holes every inch and screwing the parts together along with some sort of adhesive (epoxy?). The casting is about .300 thick so I'd need to use fairly small screws. I was also thinking about cutting some dovetails, like you'd use to to attach a drawer face.

It doesn't need to be beautiful, I can grind, fill and paint it to cover any cosmetic issues and most of the stress would be downwards, parallel to the seam.

Here's my chicken scratch drawing.
The idea is to cut section B out and attach A to C.
The baseplate is just bolted on so I could either leave it and machine it to size or remove it and leave both ends open.

http://i1019.photobucket.com/albums/af320/rmaracing/riser.jpg

Sun God
09-29-2015, 12:24 PM
Do what everyone does on a BP - create a large ring and insert it between the base casting and the swivel casting for the main arm/spindle arm.

Seems a lot less simple with some thick-wall pipe than faffing about with chopping up old castings.

spongerich
09-29-2015, 01:38 PM
Do what everyone does on a BP - create a large ring and insert it between the base casting and the swivel casting for the main arm/spindle arm.

Seems a lot less simple with some thick-wall pipe than faffing about with chopping up old castings.

Yeah.. been doing some more Googling and that might be a better option. I should be able to just about manage a ring large enough on my 10" lathe.
I also found some folks who made a solid block from a couple pieces of MIC-6 aluminum plate bolted together. That would likely be plenty flat enough and reasonably easy to cut to size/shape. I found some 2" and 3" thick offcuts on eBay and could source the material for about $50. I'd probably bolt and locktite them just to make sure that nothing ever moves, but it's a fairly small machine and I don't think that the forces involved are really all that high.

Mike Amick
09-29-2015, 02:01 PM
That's like the Picasso of chicken scratch drawings.

spongerich
09-29-2015, 02:25 PM
I decided to pick through my scrap pile and I think I've actually found a perfect candidate.

I have the table/knee from an old rusty Atlas 7" Shaper.

It's a cast iron box that's about 6x6x8 and it's already machined flat and parallel on 2 sides. There's even some t-slots on the top (which would become the side) so I can mount some holders for my drawbar wrench chuck keys, etc. It's just a little too rusty and pitted to go back into service, but it'll be just fine for this purpose after a quick bath in my electrolysis rig.

It's open at one end, but there's a thick web of iron all around the perimeter, so I think it'll be plenty rigid.

Looks like this.
http://i1019.photobucket.com/albums/af320/rmaracing/shaperknee.jpg

bob_s
09-29-2015, 02:53 PM
What are you planning to do for the tail stock|carriage/tool holder|increasing torsional stiffness of the bed?

spongerich
09-29-2015, 04:00 PM
What are you planning to do for the tail stock|carriage/tool holder|increasing torsional stiffness of the bed?

Since it's a milling machine there's neither tailstock, nor bed, nor carriage :-)

I'm not terribly concerned about the rigidity of the column with a spacer. Clausing made one as a standard option (Sadly they're NLA and even if they were, they'd probably cost a small, or not so small fortune). It's not a huge machine and the force from the cutters that fit in the 2MT collets isn't all that large.

Doozer
09-29-2015, 07:27 PM
http://i72.photobucket.com/albums/i169/kooldoozer/Machines%20and%20Stuff/SDC10585_2.jpg

Clausing did not make a spacer to my knowledge.
The taller mills got a taller turret adapter on top
of the main body. I do have the taller turret adapter
and I kicked up the head another 2 or so inches
with the M-head adapter. Maybe Johansson used
a spacer.

-Doozer

spongerich
09-29-2015, 08:38 PM
[IMG]Clausing did not make a spacer to my knowledge.
The taller mills got a taller turret adapter on top
of the main body. I do have the taller turret adapter
and I kicked up the head another 2 or so inches
with the M-head adapter. Maybe Johansson used
a spacer.

-Doozer

That's very nice.

It seems that they did change the top of the column at some point.

Mine's fairly early and the flange that attaches to the column is round at the top where the head assembly swivels, but rectangular where it meets the column. (or nearly so, it's radiused at the back). The parts diagram that I have from a later machine shows a cylindrical ring like yours that mates the column to the head. That would surely be simpler to make from a piece of thick walled tubing, but I'm feeling confident that my ghetto splicing in of the big rectangular casting will work out well. It'll be ugly as hell, but I'll trade beauty for improved functionality If it turns out to be a disaster, then I've lost nothing but time mucking about in the shop as I'm not planning on any modifications to the existing parts.

Doozer
09-29-2015, 08:49 PM
As you can see, I have a Bridgeport M-head on my mill.
I think the untimate head for these would be from a
Rockwell (Delta) mill. They are R-8 and have a very
robust spline, like a truck axle spline.

-Doozer

SGW
09-30-2015, 06:34 AM
www.speedymetals.com sells cast iron round stock by the inch. If 'twere me I'd get a chunk of that and make a riser ring. While it is possible to get cast iron tube, it turns out to be more expensive than solid bar.

Or maybe you can find a suitable piece of heavy wall steel tubing; I don't think there is any magic about using cast iron.

Oh -- cast iron doesn't weld very well. Some claim it doesn't weld, period -- the best you get is "a good glue job." It can be brazed, but you need to pre-heat the whole thing because localized heat can cause cracking.

spongerich
09-30-2015, 12:15 PM
www.speedymetals.com sells cast iron round stock by the inch. If 'twere me I'd get a chunk of that and make a riser ring. While it is possible to get cast iron tube, it turns out to be more expensive than solid bar.


I was looking at that, but the cross section is more rectangular than it is round.
I've done some welding on cast iron (gear repairs etc) and it's definitely a PITA.

I'm going to give my cast iron "box" a try. I cleaned it up a little and was hoping to get the head off of the mill tonight and have a better look at how it attaches and where the bolt holes are. From what I can see on the parts diagram, it looks like it'll be an easy fit.

Sun God
10-01-2015, 01:05 AM
I'm sorry but I still don't see why it's the box section that you need to extend. As far as I am aware this is the base casting of a Clausing 8520:
http://www.rtftechnologies.org/Design/Assets/device-images/clausing8520/restoration-pics/DSC02402.jpg

The round bearing is what the overarm and head assembly bolt to. I still don't see why it wouldn't be worlds easier to machine a spacer ring to mount onto that round bearing section, and interpose it between the base casting and the head assembly.