Adjusting a Set-Tru chuck.

[adamsgt]

I am finally getting around to mounting my Bison 6" Set-Tru chuck. The adjustment screws are not 90 degrees apart. I have to believe that this is deliberate. Therefore there must be a particular technique to use when using these screws. Any advice? The four adjustment screws are located in pairs that are 3.75" CTC and the pairs are 6.5" apart outside to outside.

 

[dmort]

There is a lot of info on line that will take you through the process.

Mort

 

[jackie schmidt]

I am finally getting around to mounting my Bison 6" Set-Tru chuck. The adjustment screws are not 90 degrees apart. I have to believe that this is deliberate. Therefore there must be a particular technique to use when using these screws. Any advice? The four adjustment screws are located in pairs that are 3.75" CTC and the pairs are 6.5" apart outside to outside.

Not sure about this one. We have several set true chucks, and the four fine adjustment screws are all 90 degrees apart.


http://benchrest.com/attachment.php?attachmentid=19352&stc=1&d=1493242806

 

[Gene Beggs]

I am finally getting around to mounting my Bison 6" Set-Tru chuck. The adjustment screws are not 90 degrees apart. I have to believe that this is deliberate. Therefore there must be a particular technique to use when using these screws. Any advice? The four adjustment screws are located in pairs that are 3.75" CTC and the pairs are 6.5" apart outside to outside.

Jerry, I have a six inch Bison chuck and was also a bit confused about the spacing of the adjustment screws. I still don't understand why they made it like that but I'm sure they had their reasons. At any rate, I love the chuck and have done my best to wear it out during the past few years.

You will quickly get the hang of dialing it in once you learn to ignore the odd spacing. No, the screws are not ninety degrees apart but they are directly across from each other. I'm not very good at explaining stuff like this but maybe someone else will chime in.

I've got a better idea; why not drive out to Odessa and I'll show you. We can also do some shooting in the tunnel. What do you say?

Later

Gene Beggs

 

[jackie schmidt]

I found a YouTube video, the holes are offset like that to clear the various parts inside the chuck.

Just teat them like you would a chuck with the holes spaced 90 degrees. Once you get used to it, it will be no big deal.

As to the other part of your question, what are you unsure of as to how to use it?

 

[adamsgt]

I found a YouTube video, the holes are offset like that to clear the various parts inside the chuck.

Just teat them like you would a chuck with the holes spaced 90 degrees. Once you get used to it, it will be no big deal.

As to the other part of your question, what are you unsure of as to how to use it?

I've been googling but hadn't found that video yet. Well, I thought that if they had a reason for that unusual hole spacing , that there must be an unusual technique to use them. As the hole pattern results in a shallow X I'm trying to envision how the force applied through one screw is applied to the chuck. Can't quite wrap my brain around it yet. One thought comes to mind is that you probably end up only rotating the chuck 180 degrees when centering. Well, I guess I'll see how it works once I get is assembled and mounted.

 

[adamsgt]

There is a lot of info on line that will take you through the process.

Mort

So far I haven't come across too much yet. I did find one site where a discussion revealed that you don't loosen the three bolts that mount the chuck to the back plate when using the adjusting screws. Did you find that in the info you came across?

 

[adamsgt]

Jerry, I have a six inch Bison chuck and was also a bit confused about the spacing of the adjustment screws. I still don't understand why they made it like that but I'm sure they had their reasons. At any rate, I love the chuck and have done my best to wear it out during the past few years.

You will quickly get the hang of dialing it in once you learn to ignore the odd spacing. No, the screws are not ninety degrees apart but they are directly across from each other. I'm not very good at explaining stuff like this but maybe someone else will chime in.

I've got a better idea; why not drive out to Odessa and I'll show you. We can also do some shooting in the tunnel. What do you say?

Later

Gene Beggs

Yeah, I remember watching you dial in a barrel when I spent a few days with you a few years ago. It did look pretty easy. Seeing as we weren't able to get together when I was on my way to the Cactus this year, I'd love to make another trip to Odessa. I've got two family related trips in May but pretty free after that. I'd like to get a look at your new design for your tuners. Once I get the lathe configured I'd like to start threading some muzzles for tuners.

 

[Gene Beggs]

So far I haven't come across too much yet. I did find one site where a discussion revealed that you don't loosen the three bolts that mount the chuck to the back plate when using the adjusting screws. Did you find that in the info you came across?

Jerry, sounds like you are trying to make something hard out of this and getting ahead of yourself. If your chuck has three 'bolts' as you say on the backplate it's a D1-4 camlock. These aren't bolts, they are camlocks and have nothing to do with dialing in the chuck. If you can't find someone local that is familiar with it take my suggestion and fly out to Midland on Southwest. We can get you all checked on mounting and dialing in. We are past due for a visit anyway. What do you say?

Gene Beggs

 

[dmort]

So far I haven't come across too much yet. I did find one site where a discussion revealed that you don't loosen the three bolts that mount the chuck to the back plate when using the adjusting screws. Did you find that in the info you came across?

Yes. There is discussion on the Home Shop Machinist you might find helpful.

Mort

 

[adamsgt]

Jerry, sounds like you are trying to make something hard out of this and getting ahead of yourself. If your chuck has three 'bolts' as you say on the backplate it's a D1-4 camlock. These aren't bolts, they are camlocks and have nothing to do with dialing in the chuck. If you can't find someone local that is familiar with it take my suggestion and fly out to Midland on Southwest. We can get you all checked on mounting and dialing in. We are past due for a visit anyway. What do you say?

Gene Beggs

Gene, there are three bolts that hold the chuck body to the back plate. They go through the chuck body from the front to threaded holes on the back plate. On a site that I visited, there was a discussion about loosening these bolts slightly before using the adjustment screws. The consensus was that these bolts be tightened firmly when assembling the chuck body to the back plate but not so tight that the adjustment screws couldn't move the chuck body. I know how the D1-4 camlock works.

Gene, I'd just as soon drive down there. The skies aren't all that friendly anymore. Besides it's a pretty nice drive until you get close to Midland. However, every time I pass through Sweetwater they seem to have added a hundred more wind turbines. I don't think there's one ridgeline that isn't strung with the wind turbines as if they were Christmas lights.

 

[adamsgt]

Yes. There is discussion on the Home Shop Machinist you might find helpful.

Mort

I believe that is the discussion I was referring to. I'll check it out though to be sure I didn't miss something helpful. Just went through my browsing history and went back to that discussion on Home Shop Machinist to verify what I got from it. I didn't look for other discussion about this on the web site site but will do so.

 

[adamsgt]

Here's a post from the discussion on Home Shop Machinist: "I use the nudging screws only to shift the body of the chuck.
after each shift, I back off the nudging screw.
As mentioned the face-bolts are kept at a soft tight and left alone.

When I'm dead nuts, I bring the nudging screws all back to contact and just
a tiny snug, Done.

A couple of new terms here, "nudging screws" and "soft tight" . I really like the description of "nudging" the chuck body. That really makes it clear what you're doing in this case. What I glean from this thread http://bbs.homeshopmachinist.net/threads/65152-Bison-Set-Tru-Chuck is that when I start my procedure to just back off the nudging screws, make the adjustments and then snug up the adjustment screws. This, of course, is predicated on having the chuck body at "soft tight". Obviously I'm going to have to develop a "feel" for the "tiny snug" Have I got it right?

 

[dmort]

Yes, you read the same thing I did.

Let me know how it works out. I'm thinking about buying one.

Mort

 

[Randy Perkowski]

Set Tru Chucks

Over the past 40 years I have used at least 10 different set-tru chucks. I have 2, Buck adjust tru chucks, one 3-jaw, and one 6-jaw. Both have been used for chambering. The adjusting screws being something other than 90 degrees as Jackie said, you will get used to. I believe that tension on the adjusting screws are necessary to not only indicate in your part but to also hold the chuck in position while machining. Without tension on the screws a minor bump or a non-concentric piece of material can knock the things out of wack.

I have also found that when installing the chuck for the first time a light cleanup facing pass should be taken on the chuck mounting surface. This ensures that the mounting face is perpendicular to the spindle rotation. If using a camlock chuck, make sure it is loaded into the spindle with the same orientation. I have seen some back plates that would not repeat if they were mounted with a different angular relationship. Marking a reference line on the chuck and back plate that are lined up every time will ensure repeatable accuracy. If using a threaded mounting, it should be self locating and only need a light face cut one time.

 

[adamsgt]

Yes, you read the same thing I did.

Let me know how it works out. I'm thinking about buying one.

Mort

My Set-Tru is a 6 1/4" 3 jaw on my 12X36 lathe. Gene Beggs has a bigger 6 jaw on his bigger lathe . When I was watching him use his it was really slick. Hope I get as good with mine as he is with his.

 

[adamsgt]

Over the past 40 years I have used at least 10 different set-tru chucks. I have 2, Buck adjust tru chucks, one 3-jaw, and one 6-jaw. Both have been used for chambering. The adjusting screws being something other than 90 degrees as Jackie said, you will get used to. I believe that tension on the adjusting screws are necessary to not only indicate in your part but to also hold the chuck in position while machining. Without tension on the screws a minor bump or a non-concentric piece of material can knock the things out of wack.

I have also found that when installing the chuck for the first time a light cleanup facing pass should be taken on the chuck mounting surface. This ensures that the mounting face is perpendicular to the spindle rotation. If using a camlock chuck, make sure it is loaded into the spindle with the same orientation. I have seen some back plates that would not repeat if they were mounted with a different angular relationship. Marking a reference line on the chuck and back plate that are lined up every time will ensure repeatable accuracy. If using a threaded mounting, it should be self locating and only need a light face cut one time.

I plan on doing the prep work you indicated. I've already installed a Bison collet chuck and prepped in that way.

 

[TRA]

Here's a post from the discussion on Home Shop Machinist: "I use the nudging screws only to shift the body of the chuck.
after each shift, I back off the nudging screw.
As mentioned the face-bolts are kept at a soft tight and left alone.

When I'm dead nuts, I bring the nudging screws all back to contact and just
a tiny snug, Done.

A couple of new terms here, "nudging screws" and "soft tight" . I really like the description of "nudging" the chuck body. That really makes it clear what you're doing in this case. What I glean from this thread http://bbs.homeshopmachinist.net/threads/65152-Bison-Set-Tru-Chuck is that when I start my procedure to just back off the nudging screws, make the adjustments and then snug up the adjustment screws. This, of co

None of my Adjust-True chucks are used while the face bolts are not tight. That sounds like a recipe for disaster. I've seen guys, who don't have to pay for their equipment, use a allen wrench with a piece of pipe and torque the chuck into position. Do that a couple of times and you have a warped chuck that is headed for the scrap pile. A lot of machinists have little tricks of the trade that tear up the owners equipment, as they are too lazy to do it right. Older Buck chucks had 6 face bolts, new ones have only three. You do not leave them loose and operate the machine. .

You adjust a chuck similar to tramming in a mill head. Loosen the bolts, adjust the head back in true then retighten the bolts. You find out in a hurry how precise your equipment if you have to keep loosening, adjusting, tightening, and the chuck goes back out of true. If it's not been abused it will stay put when you tighten the "face bolts" back up.