Cx701 lathe report

[Ghosty]

Brian,
I like the use of the piece of wood, get it centred and the length before even looking at cutting the scale to the correct length.
I would love to put DRO's on my lathe and mill, but my budget for the next couple of years prevent that.

Cheers
Andrew

 

[petertha]

I found some old pics I had stashed in a document. Some potential ideas to float around as you are working out a plan.

- I suspect you will find that your casting surfaces will rarely give you a perfect datum to mount a plate or fixture that will align perfectly to what will be the final stage = tweaking the encoder head & scales into alignment with a dial indicator. Yes you can shim and that may still be required in certain areas. But if you can make some mounting fixtures that will allow it to be screwed into the casting 'however it lands' but then facilitate independent adjustment in X,Y,Z direction you will find the whole tuning in process goes smoother. Plus in the event you have to remove DRO (count on it) it will give you a way to tweak it back into position without repeating the rigamarole. So in that regard, have a look at the Newall end post (the black thingy at the end of the encoder rod). I know your scales are different but what I'm trying to illustrate is its a simple post + hole + clamp slit combination that facilitates adjustment in 3 different dimensions. Everything uses 1/4-20 screws. And even the outboard facing ones are tapped which gives you something to mount covers to. (Yours might be different in this regard).

- check that you don't inadvertently cover up your lubrication nipples or have a contingency plan

- re the bracket mounted on saddle in existing holes, I had this idea which was a backup plan never invoked. Instead of just bolting on the DRO plate & kissing the travelling steady goodbye forever, I envisioned making special bolts with extended hex heads & similarly tapped on the hex ends. The idea is you still have the same bolt hole pattern exposed to mount the travelling steady if regquired. Just a thought.

 

[Brian Rupnow]

I'm not sure where the day went, but it has whizzed by quickly. I only made one little bracket (the green one), fitted it, and drilled and tapped the cross-slide for the magnetic scale. In order to cover the full range of cross slide travel, the scale ended up being about 3/4" longer than the cross slide. In order to center the scale in relation to the read head (which is bolted to the saddle using the tapped holes originally intended for the follow rest) the scale had to set in from the front of the cross-slide 3/16" and extend out past the back of the cross slide by about 1". The front attachment point was a simple tapped hole in the cross slide. The other end required the green bracket to pick up the hole in the other end of the scale. This meant tapping two holes in the far end of the cross slide. It just fit into my milling vice with about 1/2" spare room between the top of the cross slide and the tip of a the tap drill which was used for the two #8 screws in the back end. I have no logical reason why it took the entire day to get this scale installed, but it did. Tomorrow I will go about milling the top of the read head bracket to get it low enough that the read head sets in the correct relationship to be centered on the scale vertically.

 

[Brian Rupnow]

The read head bracket has been cut down to the correct size, and the read head installed. The scale has been checked for level and parallelity in two plains, and a very temporary hook up to the display shows that the numbers are indeed going up or down as I move the cross slide. That is a big plus for me. Now I will mount the swarf guard for the X axis (cross slide) and then move on to the z axis scale and read head mounting.

 

[petertha]

Just for curiosity, how does your DRO measurement compare to winding your cross slide windings? And which one will you believe? (I'm joking). Does your DRO box have provision for compensation, or how will you independently verify displacement?

I've always found it interesting that on a lathe X=cross feed and Z=longitudinal. Seems counterintuitive to what we were taught in elementary school. Then on a mill its back to X=left/right Y=fore/after and Z=up/down. Go figure. I've probably been posting incorrectly from the get-go but I ain't going back to edit them now!

 

[Brian Rupnow]

And finally, here we are with the swarf guard in place. That pretty well finishes the install of the cross slide DRO. I may have to drill and tap somewhere to put a cable restraint in place, but I will leave that for later. The next job will be the Z axis slide which fits to the back of the lathe. That one is going to be a pain, because I have my lathe bracketed to the wall, and all the bracketing and backsplash have to come off and the lathe has to be moved out far enough from the wall to let me in behind it to work comfortably
.

 

[Brian Rupnow]

Petertha--I don't know if the dro display has provision for compensation or not. I'm too busy installing scales and read heads to worry about that right now.---Brian

 

[petertha]

Ah, OK. The thing is, if its not reading correctly for whatever alignment reason, you might be undoing some of that fine work to tweak things. But I understand you're probably focused on getting it installed now & will tune it in later.

Yeah, I know the feeling of crawling around a lathe parked close to a wall. Fortunately I was able to squeeze in there. If I ever built another lathe stand I'd make provisions for some jack wheels. Anyway, if you do end up repositioning lathe, remember to go back & re-check levelling (more correctly called twist). It doesn't take much of a difference & you are cutting tapers.

 

[Brian Rupnow]

The 3 brackets for mounting the read head on the Z axis are shown here, unmodified. I had to drill and tap two 1/4"-20 holes in the saddle to mount the top block. You will see that I have partially covered the rectangular hole in the saddle dovetail. It's alright--nothing comes out thru that hole. I have had the topslide to the full extent of it's travel both directions, and nothing has to come out thru that hole. These brackets hold the read head, which in turn determines where the scale gets mounted. As you can see, I am going to have to modify the slotted piece which hangs from the block attached to the saddle. I will cut it off just below the slots and add two shorter slots below where it is cut off. This will keep it from sticking up above the block attached to the saddle, and will raise the read head a couple of inches. I don't want the scale to be right down at the bottom of the lathe, where all the swarf and chips end up.

 

[Brian Rupnow]

The Z axis read head brackets have been modified and bolted in place. I have a stack of 1 2 3 blocks and parallels in place at each end of the lathe to temporarily support the scale in place. I can use one of the stand-off scale supports that came in the kit, but I have to fabricate one that is a bit thicker for the near end of the lathe. This is not rocket science, nor is it too physically demanding, but tonight my old arse is dragging!! I'm done for today. Hopefully tomorrow I will get the scale mounted and start looking for the best place to mount the display panel.

 

[Brian Rupnow]

The new thicker mounting plate for the near end is finished and the scale has been mounted. There is a raised boss where the bracket is mounted at the far end of the lathe that doesn't show up well in the picture, and that was why I had to make the near end bracket thicker. All of my drilling and tapping is finished to mount all of my brackets, and I'm glad that is over with. I don't break taps all that often, but there is still a high pucker factor involved when drilling and tapping somethin "free-hand". now I have to use my test dial indicator and confirm that the scale is parallel in two planes to the rear "way" of the lathe. If it isn't, there are slots in most of the bracket connections and jack screws in each mounting pad to get them level and "true" to each other.

 

[Brian Rupnow]

Z axis is all mounted and dialed in. Numbers on display go up or down with carriage travel from end to end. I'm going to grab some lunch and then mount the z axis swarf guard.

 

[Brian Rupnow]

I'm getting right down to the wire here. The rear swarf guard is installed. I wish I knew how well my little pipe and flange weldment was going to work for a pass-thru in the pan under my lathe. I guess I can go ahead and install it, and if it doesn't work well I can festoon the cables some other way. I hate the thought of a whole snarl of cables just laying in the pan of the lathe. That is just asking for trouble.

 

[Brian Rupnow]

So, after another days slugging, the scales, swarf guards, and read heads are finished. The little "pass thru" that I made is gasketed, siliconed, and mounted to the lathe pan, and the cables routed thru it. I got lucky on that one---I built the "pass thru" before I had the cables that run thru it. Luckily, the end connection on the cables fitted thru it okay. The display is mounted, and I "think" that everything is going to fit when I move the lathe back into position. I may even be able to re-use my sheet metal splash guard that goes on the wall above the lathe backsplash, because the cables are routed around the end of the lathe and up to the display. I have to put some P clamps on the cables to take any strain off the point where they attach to the read-heads. I may have to do a little creative carving on the lathe backsplash before it can be re-installed---I'm not sure yet. Hopefully, tomorrow will finish this up.

 

[larrydoucet1946]

I'm getting right down to the wire here. The rear swarf guard is installed. I wish I knew how well my little pipe and flange weldment was going to work for a pass-thru in the pan under my lathe. I guess I can go ahead and install it, and if it doesn't work well I can festoon the cables some other way. I hate the thought of a whole snarl of cables just laying in the pan of the lathe. That is just asking for trouble.

I got the I believe 12x24 from busy Bee I bought it for a hobby second hand but in very good condition 1 horse power gives all the power you need it's got two gear shift. I didn't know much about lathes but I like it,I already had the milling machine I order some tooling from China Hong Kong very cheap and good stuff but sometimes hard to get it gets lost in the mail easy. I get these on eBay through PayPal so I don't have to worry. I'm going to email the buyer if I can't get it insure by air mail and a tracking number,I'm from Nova Scotia.

 

[Brian Rupnow]

There is one "dirty little secret" involved with cutting these scales to a shorter length. The end caps are attached to the aluminum scale extrusion with 3MM diameter bolts. When you shorten the scale, you don't have to drill and tap new holes because the "hole" is actually a formed slot in the extrusion that is open on one side.---all you have to do is run a 3 mm tap down the "hole" and put in new threads.--and here is the rub---I bought a brand new tap, cut the cross slide scale to length, and carefully (very carefully) ran the tap down full depth of the threads on the tap, reversing the tap every turn to break the chip. To break a tap off in the end of the scale would be a disaster!!--And then--When I went to remove the tap, it only backed out about 1/4 of a turn and froze. I could turn it back and forth about 1/4 turn, but there was no way in Hell it was coming out of there without breaking the tap. Oh No--I've screwed up the very first thing I went to do on this installation!! But wait---It's a slot, isn't it. So, get a flat bladed screwdriver, pry the slot open "just a little bit" down at the end of the tap, which I can plainly see thru the open side of the slot. A bit of lubricating oil, a short prayer to the DRO gods, some very careful back and forth on the tap handle, and out came the tap. Ahhhhh---Big sigh of relief. This so un-nerved me that I didn't cut the Z axis scale. The Z axis scale is about 1 1/2" too long, but I wasn't going to test my luck again. I am going have to cut a pocket into the lathe backsplash to accommodate this "too long" scale on the end nearest to the headstock. I can patch up around the point where the "too long" scale interferes and requires some minor trimming of the backsplash, but no way do I want to have to buy a replacement scale because I broke a tap off in the end of it.

 

[Brian Rupnow]

So, after $1240 Canadian, and 3 1/2 days of what seemed like damned hard work, everything is back to normal. Everything fits and is in the same position it was when I started. I opted to buy the 5um read heads for both axis. I could have paid $200 Canadian funds more and got the 1 um read head for the cross slide, but for a hobby lathe I didn't think it was worth it. I haven't used the lathe yet, just ran the cross slide and the carriage and watched the numbers scroll up and down on the display. I'm whipped, and don't plan anything more for today.--Hope you enjoyed following along.---Brian

 

[Blogwitch]

If you have got the read heads and gibs set up perfectly, 5um will display down to 2/10ths anyway very accurately.

Very few people work to that tolerance.

John

 

[petertha]

Looks good. Welcome to Club DRO. You'll love it.

 

[bazmak]

2/10ths is bearing manufacturers tolerance,and then ambient air temp
variations becomes a problem.Dont worry too much enjoyed your excerlent post Brian