PDA

View Full Version : Lathe Stop



Magnum164
05-07-2011, 08:28 PM
I need to make about 10 parts on the lathe all the same length and as accurate in length as I can get them. I have a Grizzle G0602 and the parts are .375 AL .925IN long. I have searched for lathe stops but most are mounted on the tail stock and my tail stock will not move close enough to use it.

What is the best way to set up your lathe for this? I need a good way to measure from the cutoff tool to some sort of stop. Right now I am using a magnetic indicator holder mounted on the cross slide. But I am rough cutting the parts and then final cutting length in my CNC.

S&S_ShovelHead
05-07-2011, 08:44 PM
Like a carriage stop?

http://www.projectsinmetal.com/carriage-stop-for-a-grizzly-g0602-10x22-lathe/

Magnum164
05-07-2011, 09:00 PM
Thanks! I was actually looking at that site earlier but missed that.

Carld
05-08-2011, 11:48 AM
To know how far your backing off the screw you will need a wheel divided in thousandths. Here's what I built.

http://i82.photobucket.com/albums/j276/yeathatshim/carriagestop.jpg

Peter.
05-08-2011, 01:10 PM
I don't have a micrometer stop so I just clamp a piece of scrap steel to the lathe bed to stop the carriage against and then fine-adjust using the compound. You can use a long bar clamped to the tailstock as a material stop as you feed the stock thorugh.

Magnum164
05-08-2011, 02:22 PM
yea, the material stop is what I need more than anything. After thinking about is a carriage stop will help with repeat cuts. But a material cut and a way to measure and setup the stops is important. Right now just measuring with a pair of calipers and eyeballing which there must be a better way.

Boucher
05-08-2011, 02:52 PM
Fortunately my lathe came with a factory Micrometer Stop. This has proven to be a very useful tool. This would not be that hard to make and is definitely worth the effort.

Micrometer Stop

http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0050.jpg


Bottom View
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0051.jpg


90 Vee and Bottom Clamp
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0052.jpg

danlb
05-08-2011, 03:22 PM
It's not too hard to use a carriage stop combined with a spacer block to allow you to use the tool you will cut with as a stop when feeding.

In use, Set the stop where you want the carriage to stop at the end of the cut. Add a block the same length as the cut, and use that to reset the tool (carriage) to the outboard end of the cut. Extend new stock so it reaches the cutting edge. Ready to go.


Dan

Carld
05-08-2011, 03:30 PM
Sometimes I use the screw to set the travel. Run the screw out far enough to back it off, bump the carriage against the screw then back the screw off the required distance if it is under 1". When more than an inch I use adjustable parallels to set the gap.

There's more than one way to set a gap or skin a cat. :eek:

J.Ramsey
05-08-2011, 03:38 PM
My poor boy carriage stop with DI.



http://i1200.photobucket.com/albums/bb324/buellx1rider/shop%20tools/StopSmall.jpg

Carld
05-08-2011, 04:19 PM
Ohhh, that's nice JR. You really don't need a wheel marked in thousandths with that.

J.Ramsey
05-08-2011, 07:16 PM
"You really don't need a wheel marked in thousandths with that."

Thanks for the complement.

The first stop I made was similar to yours and I used a left over B-port down feed stop nut, but figured there must be something easier to use, a buddy of mine showed me his "didgy-on-a-stick" so I made this to fit my lathe.

These pics are a little better than the earlier one I posted.


http://i1200.photobucket.com/albums/bb324/buellx1rider/shop%20tools/carriagestop.jpg



http://i1200.photobucket.com/albums/bb324/buellx1rider/shop%20tools/Carriagestop1.jpg

Toolguy
05-08-2011, 09:14 PM
That's a pretty nice carriage stop for a poor boy!;) If you're trying to make a bunch of parts all equal length, don't forget about a 5C collet with a stop or a stop in a 5C collet chuck. You can cut your parts off on the bandsaw, face one end, then put the faced end to the stop and face the other end. Very repeatable.

Magnum164
05-08-2011, 11:43 PM
Thanks for all of the carriage stop ideas. Anyone have any pictures of material stop ideas?

I don't have a 5C holder yet for the lathe. But I am looking for something like on a horizontal bandsaw stop. Just push the material up and cut it off. I am thinking the lathe will be a lot easier than the bandsaw due to it's size.

Probably a combination carriage stop and material stop. I will have to look into how people are using DROs. There should be an easy way to set the length of cut on the lathe.

photomankc
05-09-2011, 01:27 AM
That Projects in Metal carriage stop is mine. I use the snot out of it and in conjunction with a magnetic backed DTI I can always get the length +/- 0.002" and normally within 0.001". If I need to do several the same lenth I use the DTI at the back-end to give me the start point at "0" on the dial. Then load the material and use the tip of the tool as a work stop and carefully close up. Now run forward hit the stop and part off. That's generally been good enough for my use.

One suggestion. If you make that stop..... might make it wider and a little thicker. I've noticed the clamping force is taking a toll over time.

BillDaCatt
05-09-2011, 02:16 AM
I have never used one of these so forgive my ignorance on the proper use of a "carriage stop". Would it be correct to assume that these are not intended to be used with the power feed? I ask because it would be nice to have the carriage stop and the half-nut disengage automatically when cutting threads, but my brain is saying "this won't do that". Or will it? :confused:

Astronowanabe
05-09-2011, 02:52 AM
I have never used one of these so forgive my ignorance on the proper use of a "carriage stop". Would it be correct to assume that these are not intended to be used with the power feed? I ask because it would be nice to have the carriage stop and the half-nut disengage automatically when cutting threads, but my brain is saying "this won't do that". Or will it? :confused:

I used a Hardiage that has that feature builtin, almost too easy. But now if the carriage stop in place and am powerfeeding, need to use the hand on disengage lever and butt in puckered method.

photomankc
05-09-2011, 09:30 AM
I used a Hardiage that has that feature builtin, almost too easy. But now if the carriage stop in place and am powerfeeding, need to use the hand on disengage lever and butt in puckered method.

Indeed. I've had one crash because I let it get too close and then the lever bound and it drove the carriage into the stop. Since the machine is only 1 China HP the machine stalled before stuff started snapping. The stop was toast though. It did it's darnedest to rip it right off the machine. I did mine in aluminum for that reason though. If there is a disaster, I'd prefer the stop die rather than it tear up the ways.

I've seen some cleaver ways to set it up to disengage the feed. With these simple guys you can use it with power feed but you better be there and be ready to pull the lever.

Richard Wilson
05-09-2011, 09:34 AM
I have never used one of these so forgive my ignorance on the proper use of a "carriage stop". Would it be correct to assume that these are not intended to be used with the power feed? I ask because it would be nice to have the carriage stop and the half-nut disengage automatically when cutting threads, but my brain is saying "this won't do that". Or will it? :confused:

No it won't, unless the lathe has been built with that facility in place. Some have a built in 'knock-off' on the power feed screw but not the leadscrew, the UK Raglan for example. What the repeatability tolerance is like using these stops, either under power or hand feeding I can't tell you. When I was using a very well worn Ward 2A capstan many years ago, how hard you ran the carriage against the stop had a definite effect on component length.

richard

Magnum164
05-09-2011, 12:07 PM
That Projects in Metal carriage stop is mine. I use the snot out of it and in conjunction with a magnetic backed DTI I can always get the length +/- 0.002" and normally within 0.001". If I need to do several the same lenth I use the DTI at the back-end to give me the start point at "0" on the dial. Then load the material and use the tip of the tool as a work stop and carefully close up. Now run forward hit the stop and part off. That's generally been good enough for my use.

One suggestion. If you make that stop..... might make it wider and a little thicker. I've noticed the clamping force is taking a toll over time.

Thanks for the info. Guess I will have to put a magnet on my DTI and try it out and see what I can do. I cut the parts but the accuracy was not what I needed. Parts should have been 23.5mm but ended up 24.5mm. I am thinking I bumped the material a little to hard against the magnet mount. But having a DTI to "zero" in would be better.


Now just gotta work on my parting off so I don't end up with dimples on my parts and have to clean them up. Probably inevitable, but I have to finish up clean since I am drilling/tapping each end.

Paul Alciatore
05-09-2011, 01:18 PM
Thanks for all of the carriage stop ideas. Anyone have any pictures of material stop ideas?

I don't have a 5C holder yet for the lathe. But I am looking for something like on a horizontal bandsaw stop. Just push the material up and cut it off. I am thinking the lathe will be a lot easier than the bandsaw due to it's size.

Probably a combination carriage stop and material stop. I will have to look into how people are using DROs. There should be an easy way to set the length of cut on the lathe.

For positioning the stock material (rod?) I use a combination of two other tools. Since I have a quick change tool holder that holds the position of a given tool well, the tool can serve as a stop if it is simply cranked in to the center. It is best to use a tool that is mounted square to the lathe axis and crank it in until the flat side of the tool is on the center line to give a nice flat area for the stop. I also try to use the tool I will need for the first operation on that part to save an extra tool change.

The other half of this idea is the use of a dial indicator to position the carriage for this operation. So I jot down the DI reading for stock positioning, crank the carriage to that position, change to the choosen tool and crank it in to the center, and then I simply slide the stock against the tool. Done. And I am ready for the first turning operation on the part.

Another technique I use with collets is my shop made collet stop. It is mounted to the spindle instead of the usual internal collet threads for greater accuracy. Remember the collet is tightened by drawing it into the collet holder, so it is moving along the axis and the exact stopping position is partially determined by the diameter of the part, which can vary. Worse yet, this variation in diameter is amplified by the taper of the collet so the positional error is perhaps two or three times the difference in diameter when using a collet mounted stop. My stop eliminates this problem by mounting it to the spindle (actually to the collet closer which is in the spindle) instead of the collet so the position is always the same. Here are pictures:

Here it is assembled in the collet holder with a collet in place. The tip of the stop rod can be seen proturding from the collet.

http://img.photobucket.com/albums/v55/EPAIII/P1010008-2.jpg

And the parts:

http://img.photobucket.com/albums/v55/EPAIII/P1010004-2.jpg

They consist of a threaded rod with one end turned down to fit inside most of my collets (< 1/8") and the other end knurled for easy adjustment, a brass nut plate (just above the rod) that it fits in, a standard brass compression nut (top left), and a shop made aluminum lock nut (top right) to hold the adjustment. The nut plate has a bevel on it's outer edge to roughly match the internal taper of the brass compression nut. This nut plate rests against left end (well, the right end in the picture) of the collet closer tube so it's position is fixed in relation to the spindle. That collet closer tube is threaded to match the brass compression nut.

With this stop parts can be positioned in the collet with very good accuracy.