Author Topic: A boring table for a Craftsman 12" lathe (Read 76766 times)

vtsteam · « **on:** August 15, 2013, 06:41:27 PM »

I really could use a boring table for my lathe, so today I made a pattern to cast in iron. It will replace the present cross slide for boring. Maybe also for turning if I make it similar to the Myford style slide.

The size of the pattern is 8" x 4" and is about as large as I can comfortably cast with my present crucible -- with a little leeway. I put a relief down the center so I don't have to cut as much material away for the dovetail slide. I considered also casting in some recess for T-slots but decided not to.

mattinker · « **Reply #1 on:** August 15, 2013, 07:07:40 PM »

Nice to see the follow up starting!

Regards, Matthew

ieezitin · « **Reply #2 on:** August 16, 2013, 08:57:25 AM »

V----

I have the 12" craftsmen commercial 70ies model. I am curious of the fixture you have on your Atlas lathe to receive this boring plate fixture. I have wanted to add one to my own unit. Please while you document this build give some nice shots of the saddle.

My biggest gripe i have with American style lathes is they have no slotted beds on the saddle. I also have a Logan 820, it too has no standard fixture for a boring table.

This feature makes the lathe from the factory so much more versatile.

Will be keeping a keen eye on the thread.

Thank you.

Anthony....

vtsteam · « **Reply #3 on:** August 16, 2013, 09:41:12 AM »

Thank you Mattinker!

Here you are ieezitin:

ieezitin · « **Reply #4 on:** August 16, 2013, 11:44:00 AM »

Thanks for the photo...... i assumed you already had some sort of fixture already.

Are you just going to dove tail the new table and lock it in place or are you going to connect it to the cross-slide screw?

Anthony..

vtsteam · « **Reply #5 on:** August 16, 2013, 12:31:45 PM »

Anthony, it will be dovetailed with gib, and It will be connected to the cross slide screw just like the present cross slide.

vtsteam · « **Reply #6 on:** August 16, 2013, 07:53:22 PM »

Not much time to work on machine stuff today as we're getting ready to take a family car trip to Tennessee to visit friends.

I did a little work on the pattern because I really want T slots but didn't like the small amount of material between the dovetail cut underneath and the slots on top which would go crosswise. I really needed a thicker pattern. But a thicker pattern would require a lot more iron and I really feel I'm close to the limit of my crucible, after gating and risering is figured in.

What to do? I finally decided reluctantly to just fasten steel strips on top of the casting for the upper surface of the tee slots, but to mill the lower slots themselves in the casting. This would give me another 1/4" of metal between the dovetail slot and the tee slots.

It also meant I could cast in the lower slot sections, and in fact that would actually lighten the casting and require less metal. So today I milled in some slots and re-finished the pattern. First coat of paint was drying when I too a picture below, just before dark.

This will mean slightly more complicated molding since there will now be a parting line along the side of the pattern. And all sections above that had to have draft in the opposite direction -- so I had to add that. And greensand cores in both drag and cope -- but nothing too deep, so I don't think it will be a problem.

Unfortunately I'll have to wait until we get back to cast the table, so it will be awhile before I can continue here. Anyway, a little progress:

mattinker · « **Reply #7 on:** August 17, 2013, 05:08:52 AM »

Have a good trip!

Looking forward to the next instalment

Regards, Matthew

vtsteam · « **Reply #8 on:** August 27, 2013, 03:41:06 PM »

Thanks Matthew!

Back now, ready to make chips.

This morning I started the furnace, and set up the patterns for casting -- here checking spacing, which was kind of tight in my moulding boxes.

vtsteam · « **Reply #9 on:** August 27, 2013, 03:42:54 PM »

I rammed up the drag and turned it. Here you see my runner and sprue basin, as well as the table pattern.

vtsteam · « **Reply #10 on:** August 27, 2013, 03:46:38 PM »

The pattern needed to be coped down around the edges to the parting line. The riser is now in place, as is the tapered sprue dowel on top of the pouring basin. The sprue dowel has a small prass peg to fit in the basin.

The arrangement is a bit tight -- it would be better in a bigger flask. I haven't cut gates yet. The pattern has been blacked with plumbago.

vtsteam · « **Reply #11 on:** August 27, 2013, 03:52:53 PM »

I forgot to take more photos until after the pour. Here is the shake out. Pretty good casting, except for that big hole in the middle. It had sand in it and I think a bit of the greensand core had collapsed here. It's in a spot that won't interfere with the part build, and won't be visible in the final table but its a shame to have it mar an otherwise good looking casting.

I decided not to re cast the table -- I want to move on with the steam engine project and I need this boring table to do that.

vtsteam · « **Reply #12 on:** August 27, 2013, 03:59:58 PM »

Here is the table after roughing it in for further machining -- some minor flaws came to light besides the hole. These are shallow.

This face of the table gets a steel plate over it. It will be the upper surface. The tee slots are made by slotting that plate.

The recesses under are where the grooves are here. These will first be machined out square and to proper depth. I'll first fill the flaws with metal filled epoxy before machining.

The table was machined with my homemade carbide cutter detailed elsewhere. Quite pleased with the job it does on rough castings.

vtsteam · « **Reply #13 on:** August 28, 2013, 06:21:58 PM »

Not much time today, but filled flaws, milled the slots. and cleaned up ready to add the top plate.

ironman · « **Reply #14 on:** August 28, 2013, 09:48:41 PM »

Years ago I made a table for my lathe.

The only regret I have is that it was a total waste of time drilling and tapping all the holes, they are never in the right place when you what them. A far better idea is to drill the holes for every job.

If you look closely at the table casting you will see slag inclusions and blowholes.

The table was used to bore a steam engine cylinder between centres.

vtsteam · « **Reply #15 on:** August 28, 2013, 10:18:57 PM »

Thank you for that ironman!

vtsteam · « **Reply #16 on:** August 30, 2013, 09:05:34 PM »

Here I've widened the central groove with my new homemade milling cutter. I left a couple shoulders near the corners to serve as references when I cut the dovetails:

vtsteam · « **Reply #17 on:** August 30, 2013, 09:35:22 PM »

Cutting the dovetails:

vtsteam · « **Reply #18 on:** August 30, 2013, 09:39:44 PM »

First one done:

vtsteam · « **Reply #19 on:** August 31, 2013, 06:51:09 PM »

I finished the other dovetail cut today removed the new table from the mill vise and laid it on the lathe saddle, to pretend it was functional. I tried setting the 3/8" steel plate on top and then the cross slide. Pushed them up to the tailstock center to see if there was enough clearance for setting the tool height, running things back and forth to see how it all went. Of course without a gib or slide screw nut it wasn't much of a try out, but it was fun imagining. I probably would have made turning noises except for the fact that my wife might have been walking by outside!

So next thing to do was make a gib strip. I knew I had a 3' length of brass strip somewhere about the right size, but when I located it, it was the right thickness -- 1/8" but not wide enough -- 1/4".

Probably ideally it would be made of cast iron, but I didn't have anything suitable to saw out of old castings, and I wasn't about to fire up the furnace just to make some iron stock for a gib. So I rummaged around in a brass and bronze scrap barrel I bought at auction a few years ago and found a 9" long strip of what looked like bronze, about 1" wide and 3/16" thick.

Kind of soft, and had what looked like pores. I don't think it's sintered bronze, but not sure just what it is. But seems like it would have good bearing qualities, and anyway it was about the right size so I cleaned it up on the mill and thinned it down to 1/8". I'll need to miter the edges and slitting saw it to size tomorrow. But that's about as far as I got before being called away to entertain in-laws.

vtsteam · « **Reply #20 on:** September 02, 2013, 06:11:36 PM »

After reading a negative comment elsewhere about bronze as a material for gibs and thinking about the difficulty of finishing the edges in this soft easily bent strip, I decided to go with a steel gib instead.

I also decided to cut it out with a slitting saw from a wider strip to cut down on bending forces and to saw both edges out while clamped in the angle vise.

Here I'm slitting the gib stock -- the upper edge has already been cut:

vtsteam · « **Reply #21 on:** September 02, 2013, 06:13:41 PM »

And trying the gib in place on the boring table:

tom osselton · « **Reply #22 on:** September 03, 2013, 02:13:33 AM »

Looking good vsteam

RussellT · « **Reply #23 on:** September 03, 2013, 04:29:55 AM »

Well done.

I couldn't have got that far and not tried it on the lathe straight away.

Russell

vtsteam · « **Reply #24 on:** September 03, 2013, 07:37:55 AM »

Quote from: RussellT on September 03, 2013, 04:29:55 AM

Well done.

I couldn't have got that far and not tried it on the lathe straight away.

Russell

In-laws again! They arrived just as I was cutting the last 1/4" I kept at it, took a photo, and then ran up to the house to change and wash up!

Tom, Russell, thanks!!

News:

Author Topic: A boring table for a Craftsman 12" lathe (Read 76766 times)