How to setup to repeat same cut 50x

[martik777]

I need to reduce the diameter of a 2" piece of 1/2" OD to .400" for 3/4" on one end

I have a 3 jaw or collet and horizontal DRO to work with.

I'm thinking of fixing a rod inside the spindle as a stop and a carriage stop to limit the cut to 3/4". Maybe an easier way?

 

[Jimsehr]

What collet do you have? Easy if you have a 5c collet with a collet stop.
Jimsehr
If exact length is needed you can get a dead length 5c collet from Hardinge or bore soft jaws on your chuck or use Id collets. All 3 will give you dead length stops.

 

[mksj]

One of the issues with a threaded collet stop is the position when you pull in the piece can vary by a few thousandth of an inch depending on how tight you pull in the piece. A collet would be the preferred choice for that size stock in my view. If you need high accuracy for the stop position I use a through the spindle stop to so the part pulls into the same point. I would probably not use a feed, but would setup a carriage stop for the 3/4" stop position and you should be able to turn down 0.100" in a single pass. Depending on the cutter you use you may need to fine tune the DOC and also lock the cross slide. I often make parts in 10 or 20 pieces with multiple steps, so I jig up each step and do all the parts and then setup for the next step.

More recently I needed multiple pieces threaded exactly the same as to the start and stop of the thread, I used a rod in my tailstock to set the stick out from my 4J chuck to be the same for each part, i.e. the same starting point was within 0.001".

 

[martik777]

What collet do you have? Easy if you have a 5c collet with a collet stop.
Jimsehr

ER32 collet

Building some sort of stop in my spindle will take some time. I'll try the tailstock rod idea 1st. I don't need super precision 3/4 +/-.015 is ok

Thanks

 

[mksj]

When I made my ER40 Set-True chuck, I threaded the back so I could screw in a fixed stop attached to the chuck (not the collet like with 5C). Issue with ER collets is with short stock, the back of the collet can collapse to some degree. A tailstock rod or center should work. You may also at some point want to modify your ER chuck for a stop that could attach to the back.
First post is an ER40 stop, the second is through the spindle. More for ideas if you decide to make one.

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Mounting plate for the controller on my bike. John What kind of controller? And what kind of bike?

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Through the Spindle Lathe Chuck Stop for PM 1340GT

I have always found lathe chuck and collet stops somewhat lacking and difficult to use, especially with 5C and ER collet chucks. The 5C stop that I previously used, screwed into the back of the collet and stop slide mechanism was a piece of round stock held in place with an Allan set screw. So...

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[martik777]

When I made my ER40 Set-True chuck, I threaded the back so I could screw in a fixed stop attached to the chuck (not the collet like with 5C). Issue with ER collets is with short stock, the back of the collet can collapse to some degree. A tailstock rod or center should work. You may also at some point want to modify your ER chuck for a stop that could attach to the back.
First post is an ER40 stop, the second is through the spindle. More for ideas if you decide to make one.

POTD- PROJECT OF THE DAY: What Did You Make In Your Shop Today?

Mounting plate for the controller on my bike. John What kind of controller? And what kind of bike?

www.hobby-machinist.com

Through the Spindle Lathe Chuck Stop for PM 1340GT

I have always found lathe chuck and collet stops somewhat lacking and difficult to use, especially with 5C and ER collet chucks. The 5C stop that I previously used, screwed into the back of the collet and stop slide mechanism was a piece of round stock held in place with an Allan set screw. So...

www.hobby-machinist.com

Nice work!

I ended up using my MT3-ER32 collet chuck which fits my spindle bore and cut a rod to use as a stop inside the chuck. Cut is light so I can just hand tighten the collet net.

My other ER32 chuck screws on the spindle so no way to modify for a stop like yours.

Will probably take the time to build a proper thru the spindle stop in future.

 

[Jason812]

I usually use the carriage, DRO, and the toolholder body. Tool#1 is usually what I use for this if I have multiple parts. Set a zero, slide stock to touch, tighten chuck and go. Has worked well for me so far.

I have never used the tailstock for this and might give it a try.

 

[RJSakowski]

An easy way to make the 3/4" cut is to set up your carriage stop where you want to stop the cut. Use a 3/4" spacer between the stop and the carriage to position the carriage and insert the new stock so a light facing cut can be taken. Remove the spacer and turn to the stop for your 3/4" length. As far as the diameter goes, I usually just rely on my DRO reading. Sans DRO, the cross feed dial can be used.

For a second op on a partially finished parts, I will use a spindle stop. Here is my version.

Lathe Headstock Work Stop G0602

I have used a part stop in my old Craftsman lathe headstock for many years. When making multiple parts, it provided accurate positioning of the parts in the chuck and it allowed removal of parts for measurement when machining to precise lengths. When I bought my Grizzly G0602, I really missed...

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If using 5C collets with a collet stop, caution should be used. Variation in tightening the collet will result in inconsistent placement of the part with respect to the carriage. A spindle stop would be preferred for accurate replication.

 

[NC Rick]

The 5C collet with a stop and a hand closer is pretty accurate if round and accurate sized material is used. Tight tolerance stock to begin with helps. I don’t have much experience with ER collets. A stop in the 3 jaw could work.

 

[martik777]

An easy way to make the 3/4" cut is to set up your carriage stop where you want to stop the cut. Use a 3/4" spacer between the stop and the carriage to position the carriage and insert the new stock so a light facing cut can be taken. Remove the spacer and turn to the stop for your 3/4" length. As far as the diameter goes, I usually just rely on my DRO reading. Sans DRO, the cross feed dial can be used.

For a second op on a partially finished parts, I will use a spindle stop. Here is my version.

Lathe Headstock Work Stop G0602

I have used a part stop in my old Craftsman lathe headstock for many years. When making multiple parts, it provided accurate positioning of the parts in the chuck and it allowed removal of parts for measurement when machining to precise lengths. When I bought my Grizzly G0602, I really missed...

www.hobby-machinist.com

If using 5C collets with a collet stop, caution should be used. Variation in tightening the collet will result in inconsistent placement of the part with respect to the carriage. A spindle stop would be preferred for accurate replication.

Thanks for the tips.
I made a spindle stop after all. Very simple, just made a plug to fit end of spindle bore secured by a screw (there was a hole in the spindle outboard wall) which also secures the 3/8 adjustable rod