Lock quill when scraping / measuring tailstock alignment?

[jwearing]

When scraping a tailstock, and when measuring the vertical parallelism of the quill to the bed ways, is it standard practice to engage the quill lock?

I am aware that the bed clamp should be engaged, but I'm not so sure about the quill lock.

 

[eKretz]

I sure would.

 

[hvnlymachining]

Given that if looking to turn the most accurate part I would lock the quill to prevent movement, I would also lock it during scraping, and aligning.

 

[Luke Rickert]

If either the tailstock ram or base is moving when you lock or unlock it I would suggest you need to work on those parts. The neither of the rams on my lathes show any movement when locked (as in going from locked to unlocked when checked with a 1 micron indicator). With the base of the tailstock I fit them unlocked and then make sure they don't move when l locked (you are not going to get an accurate print if you distort the parts when locking them together)
Luke

 

[eKretz]

If either the tailstock ram or base is moving when you lock or unlock it I would suggest you need to work on those parts. The neither of the rams on my lathes show any movement when locked (as in going from locked to unlocked when checked with a 1 micron indicator). With the base of the tailstock I fit them unlocked and then make sure they don't move when l locked (you are not going to get an accurate print if you distort the parts when locking them together)
Luke

While I agree that the parts should not move much when they're locked, in practice there will always be a little bit of movement even if only due to flex. For there to be zero movement there would need to be no clearance and the material would need to be absolutely inflexible. If there's a large amount, then I agree that something should be done if possible. If it's very little, that decision lies with the owner of the lathe.

 

[michiganbuck]

And to be straight and parallel to the headstock, with the headstock being straight and parallel.
,and consider bed condition because at full length may not be the same as close to the chuck.

 

[MCritchley]

If either the tailstock ram or base is moving when you lock or unlock it I would suggest you need to work on those parts. The neither of the rams on my lathes show any movement when locked (as in going from locked to unlocked when checked with a 1 micron indicator). With the base of the tailstock I fit them unlocked and then make sure they don't move when l locked (you are not going to get an accurate print if you distort the parts when locking them together)
Luke

You must not be tightening that clamp that hard. The quill of my Schaublin and Hardinge HLV-H move very little when clamped. I ran a big Leblond with a 4" dia quill that moved quite a bit when clamped. You mentioned working on those parts, that is very difficult and is reserved for the most high level rebuilds, this is a rebuilding forum after all. If your quill is loose your tailstock bore is most likely bell mouthed, the only way to correct that would be a re-bore after scraping. There was a thread many years ago of someone doing it. after boring, your quill is to small, so you need to crome it then grind it. Most lathe rebuilds do not mess with the tailstock bore as doing anything is very time consuming and might not be worth the effort.

To the OP, lock that handle the same way as you would lock it when locking the quill when turning between centers. You don't lock the quill during drilling and if the quill is loose it will float and wobble around in somewhat of an orbit floating around center. Also map what the quill is doing when you clamp it, and you will get a good picture of what's happening. One other reason to lock the quill is so you don't chase alignment with a moving quill. If the quill moves a bit your true alignment will also move. One of my scraping rules is to set a target or goal and scrape to it so you can meet your spec and move on. If you turn between centers often you will understand my theory behind locking the quill.

 

[eKretz]

The advice from MCritchley above is good but I would add that one should be sure to hone the tailstock after boring if going that route. I rebuilt a t'stock on a good sized American lathe once this way (bored & honed t'stock casting; chromed and ground t'stock spindle; rescraped t'stock bottom) and also added an oil seal around the front of the tailstock spindle to try and help keep dirt out.

 

[MCritchley]

The advice from MCritchley above is good but I would add that one should be sure to hone the tailstock after boring if going that route. I rebuilt a t'stock on a good sized American lathe once this way (bored & honed t'stock casting; chromed and ground t'stock spindle; rescraped t'stock bottom) and also added an oil seal around the front of the tailstock spindle to try and help keep dirt out.

Good point!

The only machine I’ve seen with a wiper is the Monarch 10 EE. It was felt and changed it every two years.

 

[jwearing]

Thanks for the replies, everyone. Locking the spindle was my guess as well, but I wanted to check before proceeding, and I couldn't find it mentioned in the Connelly book.

I recently honed my tailstock bore, turned a new quill and lapped it to fit. I was aiming for .0003" clearance but ended up with about .0005". When extended 6" (leaving about 3" of quill engagement in the bore), the end lifts about .001" when I engage the quill lock. I'll keep scraping.

 

[eKretz]

Thanks for the replies, everyone. Locking the spindle was my guess as well, but I wanted to check before proceeding, and I couldn't find it mentioned in the Connelly book.

I recently honed my tailstock bore, turned a new quill and lapped it to fit. I was aiming for .0003" clearance but ended up with about .0005". When extended 6" (leaving about 3" of quill engagement in the bore), the end lifts about .001" when I engage the quill lock. I'll keep scraping.

.001" high won't hurt anything. Most manufacturers leave them a little high on purpose. Do you have the Schlesinger book also? That has a lot of good info too.

 

[jwearing]

.001" high won't hurt anything. Most manufacturers leave them a little high on purpose.

I don't mind if it's a little high WRT the main spindle, but it's currently angled upwards a little more than I would like.

Do you have the Schlesinger book also? That has a lot of good info too.

Good call. I have it on PDF, just looked it up and sure enough the information I'm looking for is right there on page 35. I'd really like a hard copy of this book one day.

It is essential that the tailstock sleeve be properly clamped in position while its parallelism with the carriage way is being checked (Fig. 69), because the clamping stress influences the position of the sleeve.

 

[eKretz]

I don't mind if it's a little high WRT the main spindle, but it's currently angled upwards a little more than I would like.


Good call. I have it on PDF, just looked it up and sure enough the information I'm looking for is right there on page 35. I'd really like a hard copy of this book one day.

I have found that on most lathes the tailstock is worn down in front more than the rear, probably due to the accumulation of chips and debris there that operators often push the tailstock right over. If it's only .001" high at headstock end over the length of the tailstock spindle I think I would leave the slight upward angle as it is.

 

[MCritchley]

Yep, leave that baby alone and have a beer!

 

[Peroni]

Joe for reference my "new" 16" Hendey's tailstock points up and toward the operator by .0005

 

[Turbowerks]

Up and to the operator is the way to do it helps compensate for part weight and tool pressure. When I have aligned crankgrinder head and tail stocks i go . 0002 to .0005 up and torwards wheel for those reasons. They grind much better than when they are wore and point down and away.

 

[daryl bane]

Way Oil or whatever proper oil on the spindle will also play a part in your measurements, usually for the better. .

 

[eKretz]

Good point!

The only machine I’ve seen with a wiper is the Monarch 10 EE. It was felt and changed it every two years.

Never in a million years would I have thought my dinky Colchester copy would share something in common with such a storied machine...



As far as I'm aware, it came that way from the factory. But no wipers on the tailstock ways... Which I'll be rectifying ASAP.

 

[lucky7]

^^^ seems your Colchester clone is nicer than my actual Colchester Triumph 2000. No ram seal/wiper or way wipers on my late model machine. Will be fitting way wipers when I get time.

 

[Richard King]

Seeing I am still alive, someone could have messaged, emailed or called me and I would have helped. I look at the forums at least 1 time a -day. Somehow I missed this one. All former students know I tell them in the class I will always answer any question asked after they are a student. I tell them if I don't know the answer I know several pro's I can ask. Seeing Lucky (2 classes), McCritchely (4 classes), and I believe the OP (1 class) all are students they must have forgot.

I am not a big believe in boring the TS bore after the rebuild. The person who bored it was my friend and student Robert Gosin who quit (as dozens of others) this forum because of one creep. Bob used the name VettBob if you want to look it up. He had issues boring his Monarch EE TS because the boring bar was to small and it vibrated. Many times the TS is worn and We used to rebuild it only. All my students learned you tighten all clamps before tests. On mills you raise the knee before locking it and measuring it. I teach you split / dismantle the TS on most lathe and use the unworn top of the sled and the bottom of the TS top housing as the master as it is not worn. Or if it is it's tenths. I did a few things when repairing the bore, most times I had them Sunnen honed and ground and chrome plated the quill if I couldn't buy a new one. Or I bored and bushed the bore. I used the unworn areas to indicate in the worn areas. The TS is low and pointing down as the crud wears the parts where it goes under it.
On a Hardinge TS that doesn't split you have to lower the headstock to compensate for the worn TS bottom. I didn't put Turcite under the TS of both types as it was to slippery and would move when boring.

The answer to the question is Yes tighter the lock like you do when running the lather. Common sense tells you If it the quill moved more then .001" its time to repair the bore / quill before scraping it.

Rich

PS I will be teach a class here in MN in Sept or October and giving a deal. I'll post about it separately.