<---My shocked face. I can't measure carriage travel? WHAT!?!?

[Maine Ronin]

Pardon my ignorance and over abundance of posts but I'm new to this trade and hobby. As you may have already seen, I'm shopping around for a lathe. I was looking at the Jet BD-920W:
http://www.machinetools4sale.com/shop/item.asp?itemid=3423

It looked like a nice lathe for as little as $1200, but one thing was bugging me so I called Jet directly. I asked the guy just how you measure carriage travel along the Z-axis. Does it come with a micrometer stop or do you have to buy one?

His response was... you can't! They don't sell anything and he doesn't think there's an after market micrometer stop! Is it even a lathe if you can't measure how long a cut is? Doesn't that make it more of a random part generator? Of course if I go up to the $4500 lathe I get a micro stop with a DRO option!

Sorry, I know there's probably an easy solution. I guess I got spoiled at school where all the lathes had a DRO. So is there a way to make this little lathe show me z-axis measurements or do I have to find another lathe for that option?

Thanks for helping the rook,
Adam

 

[Philjoe5]

Adam,
Not to worry - most of us have been in your position, I know I was. The easiest solution without spending the $ for a DRO is to buy a dial indicator and mount it on a magnetic base. Set the base on the swarf pan of the lathe, set the dial indicator against the carriage and you're good to go. Let me know if a picture is needed.

Good luck with your lathe purchase. The Jet 9x20 is a good place to start. I bought the Grizzly version and after 4 years I've become accustomed to its behavior.

Cheers,
Phil

 

[mu38&Bg#]

I made a lot of parts without a carriage stop. I used the compound for Z. Later, I used a simple carriage stop but still used the compound to set my Z. As most of my parts were short this worked fine. Now I have a different lathe and made a micrometer carriage stop using a 2" micrometer head.

 

[mklotz]

My (ENCO) lathe has calibrations on the carriage handwheel but I find them too coarse to be useful.

One of my first jobs after buying the lathe was to make two carriage stops for it. One attaches to the ways to the left of the carriage and one to the right. The latter is fitted with a dial indicator to measure carriage motion precisely when that is required.

I keep the compound aligned with the spindle axis. Then my procedure for turning a shoulder of a specified length goes like this.

Bring tool up to touch face of stock.
Zero compound.
Set left depth stop against carriage.
Move carriage to right and dial in specified length on compound.
Make cut until carriage touches left stop.

If you don't want to keep the compound aligned with the spindle. You can follow this procedure.

Bring tool up to touch face of stock.
Set adjustable parallel to specified length.
With parallel against carriage, set left stop against parallel.
Make cut until carriage touches left stop.

I seldom use the DI on the right hand stop.

 

[Maine Ronin]

Thanks guys. I'd heard of the travel indicator trick, but that still only gives you 2" of precise measurement. I guess you have to use measuring tape for the other 14" of travel.

It just seems odd to me that they don't at least tweak calipers or a depth gage to get at least 6" of precise measurement. Kind of like I've seen on the quill of a Bridgeport.

Please keep the ideas coming because this is really starting to bug me and I'd like a nice lathe I feel like I can use. It's just that I would pay an extra two or three hundred dollars to put an analog measuring device on the carriage of that lathe and there's no option between it and a $4500 dollar lathe :.

 

[Dan Rowe]

None of my lathes have a DRO but none of the machines I used on US merchant ships did either, but if you require it how about this one? http://littlemachineshop.com/products/product_view.php?ProductID=2015&category=
Not quite the full 20" between centers but the price is not bad.

Dan

 

[Dunc1]

Would a graduated hand-wheel on the feedscrew not do the job?
See http://busybeetools.ca/cgi-bin/picture10?NTITEM=B2227L

 

[Maine Ronin]

Thank you Mr. Dan Rowe! You've made it possible for me to keep being an impossible tolerance chasing, anal, wanna be machinist. I can't help it, I'm German. At the end of this semester's machining class I did get the "Best overall craftsmanship, but it took forever!" award. I'll have to post a picture of it.

Anyway, thanks again. I don't know why everyone doesn't buy one of those. I'm so used to seeing a readout or dial I'd go nuts without one.

Oh and Dunc, that's a nice looking lathe for a great price, but I don't see the feature you're talking about.

 

[Dan Rowe]

Adam,
Most of the work I do is close to the headstock so a 5C collet stop and and two micrometer stops rigged fore and aft of the carrage is all I need to achieve reasonable accuracy and repeatability with my South Bend heavy 10 lathe. That and an Aloris quick change tool post and I am very happy with my old iron solution.

The only really long stuff I have ever made is a few valve stems on the ship. One was a generator steam stop with a 1.5" OD acme thread made from 420 chrome molly steel. I was lucky that the ship also had a Versa-Mill. I always carried a few end mill cutters in my sea bag just in case and after trying chrome molly with a file I was really glad to have the cutters to make the square for the hand wheel.

Dan

 

[kf2qd]

Never been much of a problem. Ran lathes that had no stop on the carriage whatsoever. And could hold .002 on lengths. Requires that you use some other approaches though. One lathe had a carriage lock so I could make adjustments using he compund. Other machines just had a solid stop and you learn how to set ir and use a spacer block (and keep the end ot the carriage clean so you had a good surface to stop against. Other times I just had a feel for how much to bump it and take the right amount off. .003 can actaully be easier than .030.

The problem with stops is that it takes time to set them and when you are in production you figure out how to do it fast. That is why things have tolerances. You can get production and use the tolerance, or you can get perfect and never get the job done.

Most lathes didn't have DRO's because it was too hard to keep the crap out of them and they always required maintenance. It got to where you didn't trust it so you didn't use it. The Bridgeport mill - that was another story, could hardly use it without the DRO. The bigger mills we always used the dials and then an indicator to tweak it. Most of the time a 1" travel indicator was all that was needed. For some jobs you wanted 2" and one shop had a 4" indicator that came in handy from time to time.

I suppose you could make a stop like a turret lathe - had six screws in the face and you could rotate it from position to position for 6 different stops. Still took time to set it so it was only good for production. Had a set of spacer blocks i made in 1/64 increments to save time on setups. Stack the right combination together with a little tape and away I went.

To use an indicator you make your facing cut and then measure the part length and then adjust the position while watching the indicator and finish to length. Did it hundreds of times and made production of parts that passed inspection.

Get comfortable with your tools and youwill be suprised how much close work you can do without all the fancy stuff.

 

[tel]

Get comfortable with your tools and youwill be suprised how much close work you can do without all the fancy stuff.

Wise words indeed. It should be mandatory, IMHO, to learn the basics first, without all the gizmos and gadgets.

 

[Tin Falcon]

Adam: you are right spoiled by DROs on the lathe.
Will try not to duplicate here. for a shoulder .The way I learned was to first face the work piece.Then put a line on the part with a fat marker. just turn on the lathe and apply the marker. then set a hermaphrodite caliper ,AKA jenny caliper with either a rule or your regular digital, dial or verier calipers. Mark your line on the part again with the spindle turning. then just cut to the line. This works for most things if you need more precision on ths z axis then add a mic stop or indicator holder.
for parting to a length same as above but set parting tool on your layout line.
indicator holders or micrometer stops are nice practice projects.
no worries mate. I will say you are wise to do your homework and ask lots of questions before you put your money on the table. And you have the advantage of konowiung what a "real lathe " can do. Good luck with your decicion and purchase.
Tin