Lathe DRO

[Susquatch]

A while back I read a post by @Xyphota where he installed his crosslide dro INSIDE his cross-slide. This has prompted me to review the idea of adding a DRO to my lathe.

A DRO Scale INSIDE the cross slide has MANY advantages.

No worries about swarf and damage in the business area of the lathe. No worries about damaging the scale with the tailstock.

So I have been noodling modifications to @Xyphota's basic idea.

Here are some photos of my cross-slide as is.

Front of Crosslide. The gap is 40 thou measured with a feeler gauge. I don't know yet if it's enough for a strip of magnetic scale tape. If not, I would plan to remove just enough metal to clear the magnetic tape.

This is the cross-slide travel. About 6.5 inches.

This is the space left at full rear travel. Room for a sensor block and a short scale extension.

This is the rear of the cross slide in full forward position. The bracket is removable and I presume it's only there to keep the cross slide aligned and dirt out. I would remove it and replace it with a sensor mount that serves the original purpose as well as a mount for the sensor. Perhaps make it a mount for the bed scale sensor too.

It will be a while before I actually do this. I'd have to get the DRO, some magnetic scale tape, and complete the design.

Right now, I'm looking for suggestions and criticisms.

I'm also thinking about a similar design for the compound. The compound gap is similar but there is much less space for a sensor on a rotating compound. One thing at a time.

 

[YYCHM]

In the shop today

Yes it is some of my 4”od 4140 Just for interest sake... I just cut some of my 5" 4340 (the stuff with a hole in it) on my band saw and they took 12 minutes for a slice. I was happy with that. (Asian 7x12 saw). Your project looks like it will turn out well, it's almost as fun watching the...

canadianhobbymetalworkers.com

 

[Xyphota]

If you purchase the Aikron tape, I measured it to be ~0.068" tall. Your wing extension needs to be the length of exposed ways at full forward position (which looks to be about ~3/8" in your case) plus the width of the sensor and its little wipers.

 

[Susquatch]

If you purchase the Aikron tape, I measured it to be ~0.068" tall. Your wing extension needs to be the length of exposed ways at full forward position (which looks to be about ~3/8" in your case) plus the width of the sensor and its little wipers.

I calculated 66 thou based on the Aikron metric drawing. So your 68 thou is close enough to give me confidence. I have about 40 thou clearance now so that says I need to cut a groove about 40 thou deep and say 6 inches long at the bottom rear of my compound to give me some clearance.

Your length proposal for the scale "wing" sounds about right. I think I'd make it from steel to make sure it's solid and can handle the bumping around.

It looks like that's about all I would have before it crashes with the chip shield anyway. If I made it to look and act like an extension of the cross-slide, it might even add a wee bit of rigidity.

Right now, my biggest concern is cable stress relief for the sensor mounted under the cross-slide at the back. The cable will get bent around like crazy back there as the cross-slide rolls back and forth. I wish they had sensors with 90 degree cable exits. For now, I'm thinking about attaching it to my lamp base and perhaps even to the lamp cable so they can help each other. It would be nice to bundle all 4 cables (bed sensor, and compound sensor if I do one) together in a folding rolling loop rather than sliding around in the chip tray like the lamp cable does now.

I only say compound sensor if I do one because that is on my feature list for a lathe DRO. If I recall correctly, the Ditron DRO will determine the compound angle and do a moving cosine calculation automatically. I'll have to re-read that section in the manual. I don't think it will handle both axis though and I have no clue how that would all affect the tool library. Perhaps it's all too much to wish for.

 

[Susquatch]

Ditron will sell me the magnetic tape but it is prohibitively expensive compared to the Aikron. So I am going to gamble and place a minimum order for the Aikron and then see if it will work. If it does, then I'll get started machining a shallow slot in the top of my cross-slide. Till then I ain't tuchin nuthin!

 

[Xyphota]

Do you want my left over tape? I still have about 800mm left of the 1 micron stuff

 

[Susquatch]

Do you want my left over tape? I still have about 800mm left of the 1 micron stuff

Wow, if yours is 1 micron, that's an offer I can't say no to. I'll happily pay whatever fraction that is of your original purchase. I'll send you a PM.

 

[Susquatch]

Do you want my left over tape? I still have about 800mm left of the 1 micron stuff

The tape arrived today! Woooo Hoooo!

You are awesome Sir! THANK YOU AGAIN!

We have a storm blowing in here so I couldn't take a break to check it out right away. Had to finish plowing. When I finished, I didn't even put things away. Prolly related to my piler syndrome.....

But as soon as my tractor engine stopped, I headed for the barn to check it out! I had not expected the tape and stainless strips to be separate but obviously that makes sense.

I thought my scales were mini. Yours are smaller still! My strips are about 15mm wide. Yours is 10. Oh oh.....

But my heads are about the same size as your tape. So, with all the optimism I could muster, I set it up and, tried it. Drum roll please.....

.........

.........

.........

It worked!

The head and tape can even be misaligned a bit. I imagine the actual sensor inside the head is smaller than the head itself.

There was only one issue. I had to set my DRO Box for a 0.5 micron scale to get a proper display. I had thought yours was 1micron like mine. Maybe there is something about the Ditron scales that is different from yours.

But it really doesn't matter. It works just fine.

"All" I need to do now is order the DRO System for the lathe and install it.

THANK YOU AGAIN! You saved me a crap load of worry and fussing!

 

[Susquatch]

I'm now thinking of maybe making a taper attachment instead of just an end bracket. I don't really need a taper attachment or at least I have not needed one YET. But something has to be added to accommodate the extra travel of the read head, so it might as well be a taper bracket. That way if I ever need it, I can make the rest of it cuz the cross slide bracket is already there.

 

[TorontoBuilder]

I'm now thinking of maybe making a taper attachment instead of just an end bracket. I don't really need a taper attachment or at least I have not needed one YET. But something has to be added to accommodate the extra travel of the read head, so it might as well be a taper bracket. That way if I ever need it, I can make the rest of it cuz the cross slide bracket is already there.

bookmarked ... bring on your taper attachment. I need to see it done by someone I trust

 

[gerritv]

bookmarked ... bring on your taper attachment. I need to see it done by someone I trust

once you have your ELS you won't want to use the taper attachment, just sayen

 

[TorontoBuilder]

I'm the sort that likes to have back up options.

I wont have ELS on brother's 1440 lathe either without a lot of convincing

 

[Tecnico]

@Susquatch Recently I was trawling around the Myford site and noticed that they now embed the read head in the carriage so that there's nothing sticking out attached to the end of the cross slide and the scale/head isn't out where it can collect swarf, your lathe is bigger all around so it might be easy to you to pull the same trick? Just tossing that out there since it would be cool to do.....

D

 

[Susquatch]

@Susquatch Recently I was trawling around the Myford site and noticed that they now embed the read head in the carriage so that there's nothing sticking out attached to the end of the cross slide and the scale/head isn't out where it can collect swarf, your lathe is bigger all around so it might be easy to you to pull the same trick? Just tossing that out there since it would be cool to do.....

D

If I can figure out how to do this I will. Unless I am blinded by my current impressions (which is often the case), I don't see it as trivial though.

 

[a smile]

Do you want my left over tape? I still have about 800mm left of the 1 micron stuff

Due to translation, I'm not sure if it's magnetic grid scale or spherical grid scale or microgrid scale.

 

[Susquatch]

Due to translation, I'm not sure if it's magnetic grid scale or spherical grid scale or microgrid scale.

It is magnetic grid scale.

@Xyphota sent it to me and I have tested it. I can confirm that it works with my read heads.

Very nice stuff! But it's still not installed. Later this summer I hope to give my lathe a complete upgrade with a 3phase motor and VFD as well as DRO scales on the carriage and cross-slide. I have not decided on the compound and tailstock yet.