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Paul_Chretien
05-02-2007, 01:42 PM
I have a 12 x 36 Import lathe with a Cast Iron cross slide. The travel on the Cross Slide is limited to 5-1/2". For a Rear Post Tool Holder I need a hold down mechanism at the rear of the Cross Slide. The upper surface of the Cross Slide is flat and only contains a circular T slot for the Compound Slide located in the front portion. I would like to machine Two linear T slots, fore-to-aft in the rear portion of the Cross Slide. Has anyone made such a modification?

cybor462
05-02-2007, 02:03 PM
I too have an Import 12x36 and mine is exactly like yours. The slide is really not very thick as I just had mine off. I am making a tool for turning balls and I need to mount it to the slide. You may be able to fabricate a plate and attach it to the slide. That I might think possible. I would check in to the weight if you plan on leaving that tool mounted all the time. What I found out when I removed my slide was the lead screw nut is brass and I would not think it the best to have too much weight on the slide all the time. It would cause that nut to wear much quicker IMHO.

See if others have an opinion.

pcarpenter
05-02-2007, 02:40 PM
Yeah...same here. I have a 13x40 and there just is not much material there to go cutting in t-slots. One could argue that it would be a great opportunity to make a mess, as well. I concluded that if a rear mount "anything" ends up being important to me, that I would either drill and tap a rectangular pattern of maybe 4 or more holes and just use them directly for mounting, or mount a plate for same. The latter involves considering the thickness of your plate *now*, as you make the things that will go on them so you don't have to trim them by maybe 3/8 or 1/2" to allow for the thickness of the plate later. The plate may need to be even thicker than that if you want to put t-slots in it rather than a pattern of threaded holes.

Paul

Bill Pace
05-02-2007, 03:06 PM
Heres what I did........ wasnt exactly my first choice but it takes care of the occasional need to mount on the back-----

http://i22.photobucket.com/albums/b301/pace1980/IMG_0654.jpg

pcarpenter
05-02-2007, 03:38 PM
Bill-- I like your toggle nuts for the compound locking....are those shop made or purchased?

Drilling that many holes leaves me a bit queasy since Chinese cast iron seems pretty grainy and perhaps prone to voids. I'd hate to weaken the cross slide. I suppose for those of us who are squeamish about it we could just put in a few and use them to attach a plate with as many holes in it as we want ;)

thanks
Paul

Bill Pace
05-02-2007, 03:51 PM
They're shop made.

The wrench for the big hold down nut on the QCTP was desired by the shop fairies and consequentially I could never find it, so I made the handle up for it, and it was such a convience that I set out to devise a way to get the compound set without hunting for THAT wrench........ Took a bit of finagling to get them to close snugly at the position they are in in the pix

Paul_Chretien
05-03-2007, 02:58 PM
Thank you all for your input.
I like Bill's setup with a grid of threaded holes on the back portion of his slide. His method is quick and easy and it will meet most situations. When not in use, I assume he fills the holes with plugs to keep out any swarf.
If I choose to go with T slots, the most practical orientation for the slots is transverse, parallel with the spindle. The slots would cross the dovetail slide where the overal thickness is .85". I could machine slots for 5/16" T nuts and be shy of the bottom by .35" Decisions - decisions. It is so much easier to study the problem.
Paul

Bill Pace
05-03-2007, 03:20 PM
Yeah Paul, those holes are a swarf catcher, .... but I would think t-slots would be also. I just scrpunged in the junk drawer and found a piece of thick vinyl, trimmed to fit and glued 4 little magnets to it and its no problem that way.

Joel
05-03-2007, 03:47 PM
You can also use adjustable handles and preclude any difficulty associated with handle orientation. I had to grind a bit off of the diameter so they would clear the compound.

http://img.photobucket.com/albums/v186/JoelinTX/Compound.jpg

Evan
05-03-2007, 03:56 PM
I find it is easiest to find things by color. I color code things like wrenches by wrapping colored electricians tape on the handles so they stand out. Yellow and red are good.

rws
05-04-2007, 07:43 AM
I know one thing, y'alls machines are way too clean! :)

Great idea about the handles tho!

pcarpenter
05-04-2007, 10:45 AM
Paul-- you bring up an important concern about the holes and swarf. If they end up going through, the concern is not just with the interference of swarf in the holes, but with the swarf making it thorough to the inside of the dovetail where it will stay nearly forever, wearing away at the way surfaces.

On a related theme, I like the idea of attaching a plate better the more you guys talk about this. I suppose that if you drill a bunch of holes in the top of the slide, scratching it up may seem like a simplisitic concern. However, I agree with what Bob Warfield said of Chinese stuff: If metallurgy is an important factor, stay away from Chinese stuff. That having been said, I own a Chinese lathe and found that I have put some scratches on top of my cross slide in spite of being an anal-retentive engineer type. The only thing I can figure is that I did it removing chips or something. Likewise, where I pivot my Aloris tool post from time to time, I have made marks in the top of the compound...in spite of exercising care. In any case, this lathe is made of softer materials than say the Clausing Colchester's I have worked with here at work. Scratches are no big deal in a sense, but having a reference surface get dinged up over time is probably not good....making me favor the plate bolted to the cross slide.

BobWarfield
05-04-2007, 12:25 PM
I find it is easiest to find things by color. I color code things like wrenches by wrapping colored electricians tape on the handles so they stand out. Yellow and red are good.

yep:

http://www.thewarfields.com/cnccookbook/img/Workshop/Organization/P6293509.JPG

I also find welder's "arrow" magnets to be a handy organizational thing. There's one on the mill and the drill press to hold my Jacob's chuck keys:

http://www.thewarfields.com/cnccookbook/img/Workshop/P4023900.JPG

Also one to the right of the tailstock on the lathe for the same purpose.

I think if I was going to modify my lathe for a rear mount as is being discussed, I would bolt a piece of cast iron with T-slots rather than a grid of holes ala fixture plate. If I did do the grid of holes, I'd install liners and plugs, again as they do fixture plates. The liners let you replace the threads as needed. If you had reason for a smooth bore hole (such as a dowel pin to locate your fancy new slotting attachment), you can get smooth bore liners. The plugs are to keep the swarf and junk out of the holes until you need to use them.

I'm getting ready to modify my lathe for gang tooling. It's a CNC conversion, so the mod is probably too radical to consider on a manual, or maybe not. It's being written up here (still in the design phase):

http://www.thewarfields.com/cnccookbook/CCLatheCNCGangSlide.html

The plan is to machine a much longer (18") cast iron plate. Rather than have to scrape a new dovetail, I plan to mount linear slides on either side of my existing male dovetail and bolt the cast iron gang plate atop them. I have to re-engineer for a ballscrew anyway.

I'm going to use Hardinge pattern T-slots so I can buy their tooling off eBay. It's available pretty reasonably--cheapter than QCTP holders a lot of times. Should be a very nice addition. I'll let you know how it goes when I start in earnest.

Best,

BW

Mike W
05-04-2007, 12:29 PM
For my rear tool post, I mounted a piece of 1" held with 4 capscrews. There is a spacer between it and the tool post.

http://img.photobucket.com/albums/v110/tek798/Lathe/Reartoolholder.jpg

pcarpenter
05-04-2007, 01:12 PM
I would think that one of these cheap cross-slide tables with t-slots would be a good source of a t-slotted plate. You may have to mill off the dovetails on the bottom side, but I would think you could buy a cheapy for less that a slab of cast iron and the cost of a t-slot cutter...and there might be a lot less misery than cutting t-slots. I am guessing that even after cutting the clearance slot for the cutter with a straight cutter, there is a lot of tendancy for them to bind up and break...but I have never used one myself.

Paul Carpenter

Paul_Chretien
05-04-2007, 03:53 PM
You fellows have posted several good ideas as well as cautioned against some pitfalls.
My question to Mike W, " Is your piece of 1" bolted to your cross slide, and is your Rear Tool Post, shop made?"
The more I look into this matter the better I like drilled and tapped holes. Maybe 4 or 6 blind holes on the outside portion of the slide where my thickness is 1.40". From there I can fabricate an adapter plate with studs, T slots or whatever.

For another solution check out the "Build a Cutoff Attachment for Your Lathe" article, Dec-Jan 07 issue of Home Machinist Workshop.

Mike W
05-04-2007, 08:46 PM
Paul, the 1" is bolted down with 4 allen heads. The spacer has a couple of dowels so I can remove it and replace it without having to adjust the tool post. I did make the tool post. It is a reversed copy of the front one. I wish I knew who made that one but the tag is missing. It was easy to make, just two main pieces. I use KDK tool holders.

BobWarfield
05-04-2007, 11:01 PM
I would think that one of these cheap cross-slide tables with t-slots would be a good source of a t-slotted plate. You may have to mill off the dovetails on the bottom side, but I would think you could buy a cheapy for less that a slab of cast iron and the cost of a t-slot cutter...and there might be a lot less misery than cutting t-slots. I am guessing that even after cutting the clearance slot for the cutter with a straight cutter, there is a lot of tendancy for them to bind up and break...but I have never used one myself.

Paul Carpenter

You could be right. A decent XY table looks like $80 to $95. I paid $54 for my slab of cast iron and a T-slot cutter is about $30. However, it can be done. Widgitmaster on the CNCZone actually sells T-slotted slabs on eBay, and has documented what he has to do to make them. I think it is a question of whether you want to try your hand at it like anything else in the home shop.

In my case I have found cast iron to be a joy to machine, having used it for chuck backplates, so I am looking forward to it.

Best,

BW