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Colchester/Harrison lathes V grooves on cross slide, purpose?

sandiapaul

Titanium
Joined
Mar 19, 2004
Location
Princeton, NJ USA
I was using our 15" Colchester the other day and noticed for the 1000th time the V grooves that run along the length of the sides of the cross slide.

They can be seen in the top two pictures here:
Colchester Triumph 2000 Lathe Page 2

What are they for? Can't be to clamp something across as you would distort the slide.

Just curious...
 

Danny VanVoorn

Titanium
Joined
Nov 3, 2002
Location
St.Louis, Missouri, USA
Clamping the rear tool post table does not cause any binding/distortion. It hooks on one side and uses a strip And a couple of bolts on the other to pull it down tight on the ground top of the cross slide. It’s actually well thought out piece that along with the bed turret may well turn my lathe into a short production runner?
 

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
I suppose you could mount a coolant hose, splash guard, work light, follow rest or other stuff. Possibly a grinder on a tool post.
I have seen pictures where they mount a QC tool post back there or at least the stud to move it over when needed.

I think drilling one QC stud hole would be risky and risk cracking the piece like you say.
Bolting on a dovetail piece on each side saves a lot of work hogging out the middle of a solid bar. Removing that much from one side might cause warping
Bill D
 

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
You mount a threading tool on the rear toolpost. Mount it upside down and run the lathe in reverse. The tool cuts away from the chuck so no more crashes.
Bill D
 

TedinNorfolk

Hot Rolled
Joined
Oct 17, 2006
Location
Norfolk, UK
Later DSG have this slide as well. Where I worked in Cambridge we had a row of them,each with a drilling head permanently on the c s. Slide it up to a stop on the saddle to bring it on centre. Each tailstock had a sticker on with-Not to be used for drilling. I could see the reason-but would use the ts for putting in centres.
 

Bill D

Diamond
Joined
Apr 1, 2004
Location
Modesto, CA USA
The way Ian reading this the tool won't cut.

I think you are correct. Set it up with the tool in back, upside down and rotate the spindle so the work moves into the sharp edge. Maybe the feed direction has to be switched and not the spindle. It might also help for CCW threading.
I thin kit also effects which way the crossslide is pushed awayfrom the work.
As I recall the backlash has to be taken out opposite to the normal way as you deepen the cut.
Bill D
 

thermite

Diamond
I think you are correct. Set it up with the tool in back, upside down and rotate the spindle so the work moves into the sharp edge. Maybe the feed direction has to be switched and not the spindle. It might also help for CCW threading.
I thin kit also effects which way the crossslide is pushed awayfrom the work.
As I recall the backlash has to be taken out opposite to the normal way as you deepen the cut.
Bill D

Now you've grokked it. RH thread, LH thread, and internal as well as external threading.

Most useful if one is able to mount the rear tool (OR the front one..) to cut in either direction you might need it to do.

It isn't just threading away from a shoulder. Those, one can usually SEE.

The most important use for most of us was internal threading of blind bores. It is waay nicer to be able to position the tool while power is off, engage rotation and turn UP and OUT of a blind, flat-bottom hole.. than to have to hold the pucker-factor of trying to stop accurately as you run DOWN INTO it.

No need of yet-another "cursade" about 'ELSR" or similar handy rapid stop / rapid disengage. Yes, those can be nice-to-have. If yah got 'em.

Sanity check? Only a very small percentage of the world's hard-working lathes the last 200 - plus years ever HAD any such feature. So we don't got 'em.

Machinists by the brazillions just took "ordinary" lathes - front TP or rear- and threaded AWAY from the barrier/feature.

BFD

So we didn't really need the help of ..what we didn't even have!

Ordinary FRONT TP can be arranged to cut in reverse just as easily as a rear-mount.

I did say "BFD"?
 

winger

Stainless
Joined
Dec 28, 2005
Location
portage county, wisconsin
We have a 16.5" DoAll (Harrison) at work. We bought a Skyhook that mounts on the quickchange toolpost. Before I repaired the radial tslot for the compound I didn't trust it to pick up a 15" chuck. The solution was to mount a sliding block to hold it on the cross slide using the side v grooves.

Still seems like a better idea than to put all that stress on the toolpost and compound slide.

Dave
 

thermite

Diamond
We have a 16.5" DoAll (Harrison) at work. We bought a Skyhook that mounts on the quickchange toolpost. Before I repaired the radial tslot for the compound I didn't trust it to pick up a 15" chuck. The solution was to mount a sliding block to hold it on the cross slide using the side v grooves.

Still seems like a better idea than to put all that stress on the toolpost and compound slide.

Dave

Quite a few lathes have them. European mostly, AFAICS.

Cazeneuze's isn't even related to the rear compound "turntable" mount. Their tracers have that already covered with a duplicate of the regular front compound swivel and clamp-bolt track.

There are others. Monarch had an optional topslide with a raised rib, dovetailed, rearward, and on top. Tee slots have existed.
 








 
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