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SB9 reverse threading

J

JustaDB

Ultra Member
Looking down the road...

I have a project or two in mind (both internal & external threading) which appear to be easier to single point thread in reverse. That, & it just seems fun to try.

The shortcoming is that the SB9 chuck is threaded on. Can this be overcome? MT3 head spindle to ER collet adapter with a drawbar? Something else?

TIA
 
There are lots of posts on here about spindle thread locking methods to solve that problem. I'm not sure how to best search for them though. I'd prolly try a search using Google instead of the regular forum search tools.

Paste this into your chrome browser search field:

"Site:canadianhobbymetalworkers.com lathe threaded spindle lock"

Without the quotes of course. And substitute terms till you hit gold.
 
JustaDB said:
Looking down the road...

I have a project or two in mind (both internal & external threading) which appear to be easier to single point thread in reverse. That, & it just seems fun to try.

The shortcoming is that the SB9 chuck is threaded on. Can this be overcome? MT3 head spindle to ER collet adapter with a drawbar? Something else?

TIA
Click to expand...
An ER collet chuck on a drawbar would definitely allow you to thread in reverse.
 
canadianhobbymetalworkers.com

9" SM Utilathe Restoration

Which line are you trying to spilt it at? Red arrow or green? Looking into the bore from the front / back, do you see a step? If there is a step, you might be able to use an aluminum or brass drift and a hammer as a persuader to help it separate. My guess is there is corrosion or just old...
canadianhobbymetalworkers.com canadianhobbymetalworkers.com
 
Thx for the responses.

OK, hit a number of websites, there just didn't appear to be any even somewhat elegant solutions. Thought about the MT3/ER collet drawbar option, then wondered, "Does anybody make a 3 jaw chuck w/ a non-rotating MT3 drawbar mount?" I'm thinking this may be the better way to go, as I may need the larger diameter capability of a 3 jaw, rather than smaller ER collets.

As it turns out, yes. {spit} KMS Tools does, a 6" one. First, the reason for the qualifier. I've never dealt w/ KMS before. Get on the phone, call up the Calgary store for more info (is it in fact non-rotating, what's the drawbar size/thread, what's the chuck bore, what's the runout?) 20 minutes on ignore. Helluva way to make a first impression. Hang up, redial. Get a body. Ask to speak to a manager, need to vent a bit. Get one (can't recall his name), doesn't seem to care. Figgers. Puts me in contact w/ a Jay, who is s'posed to be their chuck "expert".

Jay confirms it's non-rotating. Ask about the drawbar size/thread. He says there is no drawbar. I tell him the description notes there is a threaded bore for a drawbar. Some "expert". Puts me on hold, pulls one from inventory, confirms there is a drawbar bore, has no idea what size/thread. There is no documentation in the box. Measures the chuck bore at ~1-9/16" & has no idea what the runout is. Again, there is no documentation in the box. Confirms it is Chinese made. I hang up.

Against my better judgement, I go online & order one. $200, on sale from $290. We'll see what we get when it arrives. At this point I give it a solid 50/50 chance of going back. I don't really need another chuck, but this one will probably only be used for threading.

It's unlikely I'll ever deal w/ KMS again. Very unhappy w/ their service. After checking elsewhere online, I went w/ them becasue I could not find another solution. Amazon had the only other one I could find listed, but no inventory.
 
How big of threads are you cutting? I had a SouthBend 10K and cut threads in reverse on more than one occasion and had no problem with the chuck unscrewing.
 
canadianhobbymetalworkers.com

Locking Threaded Chucks

Thought I'd revive this topic based on some chatter on @YYCHM's threading tool thread (see what I did there?) The perennial question of how to reverse thread on a lathe with a screw-on chuck. There's this example...
canadianhobbymetalworkers.com canadianhobbymetalworkers.com
 
JustaDB said:
It's unlikely I'll ever deal w/ KMS again. Very unhappy w/ their service.
Click to expand...
I think your expectations were a bit "optimistic", unless your local KMS store is radically different than the one in Victoria. The KMS I know (and don't love... :) ) is a place that sells mostly to local building tradespeople and home handymen. Cordless tools expertise: yup. Specs and details on a chuck with a MT shank....not so much. Great phone service - hardly ever, but definitely not on a
Saturday morning - if that's when you called.

Your workpiece doesn't need to enter the spindle - since you are going to use a MT chuck? Could you arrange some sort of drawbar to retain your threaded chuck?

It sounds like this is taking all the fun out of working with the lathe in reverse. :) I looked in to the "reversing with a threaded chuck" issue after I got my Logan and decided that it wasn't worth the trouble to spin the work in reverse. I still don't understand why my lathe came out of the factory in 1941 with a motor reverse switch. The switch remains, but the wiring was changed to forward only with a replacement motor years ago.
 
I’ve thought about making a piece with slits and a cone with a tapered insert that fits inside the chuck bore. Use a drawbar to draw the tapered insert into the cone and lock it in place.
Sort of like the sliding wedge that’s used on old style bicycle handlebars.
I may still do this.
 
@JustaDB - What kind of doc, rpm and tpi are you thinking of running? Do a bit of testing, keep the rpm as low as it will go and try some cutting in reverse and see what you can get for a DOC before the chuck comes loose. Don't forget to put a board on the ways and be prepared for if/when it does come loose. At 40 rpm you should be able to catch it.

I start at .010 doc and the closer to final thread the less doc. If I'm going up to a shoulder or doing blind internal I keep the rpm down anywhere from 30 to 80. I also use the VFD to slow down getting closer to the shoulder, I'm retired so I have time to take it slow and easy.

Just my thoughts.
 
terry_g said:
How big of threads are you cutting? I had a SouthBend 10K and cut threads in reverse on more than one occasion and had no problem with the chuck unscrewing.
Click to expand...
Don't have the projects finalized yet, but I'd estimate smaller than 3/4". I have no desire to see the chuck come undone at any speed or cut.
 
VicHobbyGuy said:
Specs and details on a chuck with a MT shank....not so much. Great phone service - hardly ever, but definitely not on a
Saturday morning - if that's when you called.
Click to expand...
He was the guy I was referred to as the, quote "The guy I want to talk to" re: lathe chucks. If he doesn't know the product on the shelves, he has no business taking calls, Saturday or not. The world doesn't stop turning because it's the weekend. I even get not knowing the runout, or possibly the size/thread of the drawbar bore, although he could have found out that w/ a bolt or tap if he really wanted to. That's what I would have done if I'd taken the call. It's called customer service. He made zero effort. Not knowing there's even a drawbar bore? Their problem, not mine.

VicHobbyGuy said:
Could you arrange some sort of drawbar to retain your threaded chuck?
Click to expand...
Had a look at all 4 of my chucks. Don't see a relatively easy way to do it.
 
JustaDB said:
Sure. But can I react, drop everything & throw on my catcher's mitt in that time frame?
Click to expand...
Just need to hit the off button, lots of time for a smoke in the middle......:rolleyes:
.... although, I must say, I have yet to find a need or desire to thread backwards....... Just give yourself a little bit of thread relief, set up a stop/indicator whatever your preference, and keep your hand on the half nuts, (not your nuts, the half nuts)....... Take a few dry runs to get the feel of things, then start with a scratch pass......:p
 
JustaDB said:
he could have found out that w/ a bolt or tap if he really wanted to. That's what I would have done if I'd taken the call. It's called customer service.
Click to expand...
Spending more than a few minutes on the phone with somebody who might not even buy anything?....If it's like the local KMS here, there were probably 5-10 customers inside the store, walking around trying to find somebody to help them spend their money. I've "been there, done that" ..standing in front of a KMS staff person while they 'shoot the breeze' with somebody on the phone. KMS= VERY poor management, understaffed store, poor customer service ..both in person and on the phone. It's the business model which works well for them, apparently.
 
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