Thread: Tail stock travel extension mod

I just got a new to me 10L cabinet style with a hard 4 ½ foot bed, and a cam lock spindle. At what I would conceder a very reasonable price. I though while I was cleaning, leveling, and rewicking. I would send the tail stock out to Steve Howell (jockofthelowveld) to have him increase the travel of the tailstock. The other issue with the tail stock was that it would not eject some of my live centers, which you all know is a PIA.
I emailed Steve with my questions and concerns about the job. He emailed me back right away and asked for my phone number and called me to answer my questions and give me his thoughts on best way of recuting the Morse taper in the spindle which I wanted to do before sending the parts out.
I had told Steve that I was not in a big hurry to get the parts back due to the other work I had to do on the lathe. I mailed them out on Nov 29 late in the day and got them back on Dec 6 which I think is great turnaround time.
In with the parts were instructions on what to do I f the zero did not line up. Mine lined up perfectly.
I am very pleased with the way that works and the depth that I can drill without moving the tail stock.
I will do my best to post a picture. If not I may have to get some help.

Dave

I like the idea of the extension and have found times when I wished I had the modification on my own 10L. I am sure that Steve is an excellent machinist and the quality of his moditication is most likely accurately machined.

I guess I just have one question about the modification and how both Steve and new owners find their use in tirning application as opposed to drilling. I know that it is best to keep the quill drawn into the casting, however, there may be times when one might run the quillout some distance which places the center farther away from the caseing throat support. If the quill is run out towards the head while doing turning, are users finding that there is more axial play between the quill lockup position and the center in the end. I guess what i am asking, does the quill, when extended away from the tail wobble or give way from the effect of turning a part.

Eric

Ibgolfr;

Tailstock quill wobble cab occur if the tailstock quill is worn and no longer has the .0005" clearance between quill and i.d. of tailstock casting. Most used SB lathes have some tailstock quill wobble when used unlocked. SB and other lathe mfgs. provided locks to secure the tailstock quill from wobble. However, one has to be careful when he/she locks the tailstock quill as it will move towards the operator side of the lathe on SB's in relationship to the amount of wear between tailstock casting and tailstock quill. I have seen SB lathes tailstock quill move as much as .003"-.004" when locked. (Place a dial indicator against your quill and lock it down and see how much it moves).

Tailstock wobble is generally a function of wear of the tailstock casting, tailstock quill o.d. and the wear of the Acme thread and tailstock quill feed screw. When I modify a tailstock quill, I make a new feed screw and a new 10tpi left hand thread in the rear of the tailstock quill.

When I make a new tailstock quill I make the o.d. of the tailstock quill to about 1.0625" to account for some of the wear in the tailstock casting. I have seen tailstock quills that I have received vary down to as little in 1.0585 in o.d.

On my 10L I have installed a 1/4" set screw (with brass tip) in the tailstock casting to oppose the movement caused by locking the tailstock quill lock. I use this when I am doing very very precise work.

However, when I do very very precise turning work, and most of the time as well, I never extend my tailstock quill beyond about .050" beyond the Zero mark on the quill. As a matter of fact, I have made a special tailstock quill that I use for this very very precise work that has the first 1/2" of the tailstock quill o.d. .0005" larger than the remainder of the tailstock quill o.d. in order to eliminate tailstock wobble without using the tailstock quill lock. Even when I use this special made tailstock quill, I use a dial indicator to make sure the tailstock quill has not moved when it is locked down. What I consider precise work on my SB 10L is turning a round bar say 1 inch diameter by 6 inches long without more than about +/- .00025"variance in diameter. Using my special tailstock quill (unlocked), I have turned a 2 inch diameter 1020 round bar 36 inches long with only +/-.00025" variance in diameter without a follow rest. I must say that I had my 10L's bed reground and added a NOS 10L saddle scraped to fit the new bed regrind.

Here's a TIP for those of you who want to do very very precise centering of a round bar in your lathe's 4-jaw (or very precise 3-jaw) chuck or collet. Instead of using a center cutting drill set in a drill chuck in my lathe tailstock, I use a #2 Morse taper end mill holder for a 1/4" or 1/2" o.d. end mill inserted into the taper of my tailstock quill. I grind a shallow flat on my 1/4" or 1/2" o.d. center drill length in order for the set screw of the end mill holder to hold the center drill in place. It makes a world of difference.

In my opinion the tailstock quill should not be used for precise turning with the tailstock quill extended beyond about 1.5 inches. If one turns heavy work with the tailstock quill extended to its limits, even if it is locked there is the opportunity for tailstock quill flex to happen--which is another matter.

The modification to extend the tailstock quill travel is for drilling work.

The opportunity for tailstock flex to occur is of course greater if one has the tailstock quill extended to 3 or 3.5 inches while turning.

On some work I use my tailstock extended as much as 3 inches and unlocked down for turning, resulting in fairly precise work (within .001 variance). I don't do this a common practice but sometimes I forget to move my tailstock quill to the rear.

However, one should not use the tailstock quill extended to 3.5 inches using the modification (locked or unlocked) for tuning work, unless one is not concerned that the work diameter will vary a thousand or two of an inch in diameter.

As always the proof is in the pudding and the experience of individuals who have had the modification to extend their tailstock quill will be best for us to hear.

I am planning to offer in the near future NEW, made in my shop, standard size tailstock quills for South Bend 9N, 10K and 10L lathes, engraved with the the standard 1/10 inch segments and numbers 0, 1, and 2" engraved or stamped on the quill, #2 Morse taper front and 10 tpi left hand acme thread in rear. It will require one to send me their tailstock quill so that I can measure it and make a new one to exact fit. I will return the old quill along with the new one. I have made some tailstock quills and it requires a great deal of very careful work, especially the cutting of the Morse taper to the center line.



Best Regards;
Steve

Steve

Very nice explanation and cited suggestions regarding the extension of thr quill when doing work. I usually keep the quill as close as possible to the "0" and apply the lock. The set screw idea is interesting and i will look at that modification.

Additionally, I have thought of using the milling holders in the tail and in the Millrite for center drilling as opposed to the chuck. I'll order a couple, modify the center drill side for the screw engagement and give them a try--this way they can set there in the rack ready to go.

Do you have the equipment to line bore the tail stock quill hole slightly, re-truing it and then cut the new quill to a new diameter?

I really like that 10L you have there-----------

Eric

Originally Posted by ibgolfr

Steve

Very nice explanation and cited suggestions regarding the extension of thr quill when doing work. I usually keep the quill as close as possible to the "0" and apply the lock. The set screw idea is interesting and i will look at that modification.

Additionally, I have thought of using the milling holders in the tail and in the Millrite for center drilling as opposed to the chuck. I'll order a couple, modify the center drill side for the screw engagement and give them a try--this way they can set there in the rack ready to go.

Do you have the equipment to line bore the tail stock quill hole slightly, re-truing it and then cut the new quill to a new diameter?

I really like that 10L you have there-----------

Eric

Eric;

No, I do not have a line bore rig for the tailstock casting. Contact Miller Machine (see sticky with links, parts and so forth on this home page) and see if they can do it. Tailstock castings also can be bored, a brass or bronze insert pressed in and then re-bored to standard SB size. Miller may have a horizontal mill where they could mount the tailstock and bore it for you. My Burke #4 horizontal mill does not have enough travel to bore the headstock the full length.

I had Miller Machine make a new B&S #9 taper arbor for my Burke #4 mill. They do excellent work.

I have a Millrite also--- after looking for good one for years. It came from Catawba Technical College in North Carollina: 1974 model with options of extended knee and 36 inch table and NMTB 30 spindle taper. However at about 1600 lbs, it is almost as heavy as a series 1 Bridgeport mill. The 30 taper is not preferred by many, but I like it and there is a good selection of quality used 30 taper tools as very good prices. One good thing about it is that you can buy new NMTB 30 taper ER-40 collet chuck and collets for it very cheap--which I did. Of course, its motor was 3-phase and I had to buy a VFD for it, which I like very much.

Steve