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form_change
03-05-2011, 03:54 AM
One of the mods I've wanted to make to my lathe was to incorporate a traverse dial. Later models of my lathe had these but mine must have been a year or two early. Tim Leech included some photos in one of his posts that showed me what to do; the parts manual had a section that I used for scaling and Tim also answered a question or two to fill in the gaps. The finished item looks like this -
http://i1140.photobucket.com/albums/n574/form_change/P1010064Small.jpg
The dial itself was a straight forward turning job. However at 83mm diameter putting the knurl on was 'interesting'. Graduations were made with a hand graving tool (from the scrap collection).
http://i1140.photobucket.com/albums/n574/form_change/P1010016Small.jpg
It's certainly not as elegant as Evan's but I figured that for a tool I'll use maybe 4 or five times (if that), what I made was good enough. The scribing tip is a piece of broken tap, reground. The length stop are just bits of flat cut to the appropriate length. I've seen plans for some with automatic indexing but that seems a lot of trouble for a occasional use tool.
The lathe needed modifying too - the disc at the rear of the dial with the mark on it is also used to preload a bearing. The handle on the bearing is now feeling a bit stiff so I may have to lap it down a bit. (Oh for a surface grinder). The main handwheel also had to be turned down. As it's around 8" in diameter, holding it proved tricky but I got there.
http://i1140.photobucket.com/albums/n574/form_change/P1010063Small.jpg
Graduations were stamped in and then given some colour with a lacquer-stick. I made up a jig from the scrap box for holding the stamps like this
http://i1140.photobucket.com/albums/n574/form_change/P1010061Small.jpg
It worked well although I think I let the project down a little with the graduation numbering - I bought a set that had the numbers that on close inspection look to be at slightly different heights with respect to the stamp outline, so the stampings are not exactly all in line. Still, it gives that traverse measuring capability.
In the Trav-a-dial thread started by Sir John, someone suggested a lathe rack may not be good enough to measure with. On this lathe the carriage moves 1" for every revolution of the hand wheel. Each graduation on the dial is 5 thou (as per the factory fitted version). Cranking the wheel, watching the dial and comparing it to a digital caliper, it was pretty good. 1 handle rev indicated 1.001" on the caliper - as graduations are 5 thou I can accept that the error is more likely to be me than the rack. There were some cyclic errors (that is, errors present at certain hand wheel positions over several revolutions) present, up to 3 thou but again this is just as likely to me not lining up the graduations properly or possibly caused by indexing errors when graduating the dial. If I want better than 5 thou in length then I can use the compound slide to do final adjustments.

Michael

hornluv
03-05-2011, 08:36 AM
That's really slick and professional looking. I've been meaning to make a new dial for my compound since the folks at the factory put 112 divisions on it instead of 100. I think they actually gave me the metric dial on an inch machine. I'm also going to make a new cross feed dial so it will read on the diameter.

Carld
03-05-2011, 08:47 AM
hornluv, if one revolution of your dial makes the compound move 112 thousandths you can't change to a dial with 100 divisions and have each mark move it .001". The travel will be 112 divided by 100 = 1.12 thousandths movement for each mark.

If you can mentally manage that while making a cut your pretty good.

hornluv
03-05-2011, 09:46 AM
hornluv, if one revolution of your dial makes the compound move 112 thousandths you can't change to a dial with 100 divisions and have each mark move it .001". The travel will be 112 divided by 100 = 1.12 thousandths movement for each mark.

If you can mentally manage that while making a cut your pretty good.


Therein lies the rub. One revolution of the dial moves the compound .100 as shown with a dial indicator, not .112. They put a metric dial on an inch screw.

John Stevenson
03-05-2011, 10:00 AM
Nice job Michael,
I had thought about the same but I have a guard on mine that obscures the handwheel.

http://www.stevenson-engineers.co.uk/files/cva%20handwheel.jpg

I find I need this to keep hot chips off my hands.
seeing as the CVA is a clone of the 10EE they copied the LH side hand wheel position whereas most British and European lathes have a RH hand-wheel where you don't have the hot chips problem.

Carld
03-05-2011, 10:01 AM
Ah, that is an issue worth correcting. Something like that would make you have to use a dial indicator when using the compound.

On worn out lathes in some shops I worked we had to use a dial indicator because the worn out nut and screw never moved it what the dial said.

J Tiers
03-05-2011, 11:08 AM
How well does the gear and rack follow the dial marks? if well made and new, I would expect it to be good, but after a while with chips, dirt, gummy oil etc, plus wear in some places, I would suppose it might be off a bit. Still likely accurate for one or two revs?

Timleech
03-05-2011, 02:11 PM
Nice job, I like the oiler. CVA didn't fit an oiler, my Metric dial is seized on the shaft, I haven't yet got around to stripping the thing down to free it, probably because I don't use that (half-metric) lathe as much as the other which is all imperial but has a DRO.

I'll try to do a pic of the original version tomorrow for comparison, it's almost as good as yours ;)
(Sorry Michael, I did say I'd send you a pic but you seem to have managed OK without!)

Tim

form_change
03-05-2011, 03:17 PM
Hornluv,
Even 112 divisions sounds screwy. If it were a metric dial I'd expect 127 divisions. Someone at the factory had some serious brain fade that day. However, a new dial is not difficult to make. I haven't got drawings for my tooling but if you want extra photos or explanations, send me a PM and I'll try to help

JT,
The correspondence seems good. I haven't got the gear to check over long lengths but on the short tests that I did, I didn't seem to gain anything (but on a well cut gear and rack you would not expect it to). The lathe is from 1954 and has seen some work, so I'd guess from new it would have been spot on. I did think about fitting a vernier scale but that's probably taking things too far.

John,
Funny you mention the hot chips, as that's one of the things that I was cursing the other day. It never would have happened on my former lathe as it didn't have the omph to send off a stream of hot blue things. I'm thinking of a couple of sheet metal guards held on with magnets so I can easily move them if they get in the way. My lathe hasn't got the clutch by the headstock which is an added complication.

Tim,
The oiler was a late thought as the handle had an oil hole which would now be blocked with the dial on. It is located there because between the 0 and 50 is the most spare space and in the dial bore I've cut a groove that lines up with the aforementioned oil hole and this is directly above. The theory is that some oil will eventually get to the handle/ shaft interface. We'll have to see.

The only design flaw I've found with it so far is that the dial locking screw is sometimes hard to access amongst all the controls on the apron. Being right handed I have it at the 3 o'clock position but perhaps it would have been better at 9 o'clock.

Michael

hornluv
03-06-2011, 08:52 AM
Hornluv,
Even 112 divisions sounds screwy. If it were a metric dial I'd expect 127 divisions. Someone at the factory had some serious brain fade that day. However, a new dial is not difficult to make. I haven't got drawings for my tooling but if you want extra photos or explanations, send me a PM and I'll try to help

Actually, I looked at it last night and there are 118 divisions (3mm on the metric dial). Regardless, it caused a lot of head scratching when it wasn't moving in as much as I thought it was, which at the time I was only looking at the big numbers and thought it was .120". So I set up the dial indicator and saw that it was only moving .100" per revolution. At least it wasn't the other way around and I was moving more than it said I was. I suppose I can just order the correct dial from Enco if I wanted to, but I think I'll make it. I'd also like to put a dial on my tailstock.

gda
03-06-2011, 09:04 AM
great build pics - thanks for posting