South Bend Mill tool holders

[BMSS]

I have a South Bend vertical mill that I bought used about a year ago, from its second owner. He had bought it from a High School that had closed its Vo-Tech. I have been doing some research, and found that there was a discussion a while back; http://www.practicalmachinist.com/vb.../t-129155.html

It seemed that most people didn't have good opinions of the SBM. For me it works fine. It suits me.

I am hoping on buying some tool holders for it, but haven't had much luck. a couple of the tool holders that I can actually read are marked;
Bakuer 30-2MT and Bakuer 30NT

Does anyone here know where I might find some tool holders for this machine? I have looked around, and haven't had much luck finding any.

[pcarpenter]

While there are lots of variants of the NMTB tool holders (most of which relate to the flange) I believe the 30NT probably refers to the 30 (National Machine Tool Builders) NTMB taper standard. Some stuff is marked 30 NAT. This standard came about in the 30's as I recall and if you have a Machinery's Handbook, you can read a bit more about it including the dimensions. The tapers for ,40, and 50 are the same as CAT 40 and 50 if I understand correctly although the flange and mount method are not the same. The CAT uses "pull studs" rather than drawbar threads for quick tool changes in CNC machines with automatic tool changers.

If you can verify this, then what you have is a standard taper and there is tooling available. I have a cheap import horizontal mill that uses the 30 NMTB taper for its standard arbors and I have some end mill holders and shell mill holders as well. I think you will find that Shars or some other import place may even have some tooling to save you money.

The MT2 item is, I assume, an adaptor to Morse Taper 2??

Paul

[alanganes]

I have one of these mills, I've had it for almost 20 years. It is less rigid than the typical Bridgeport, but I have found it adequate for all of my hobby grade work, and never felt a burning need to upgrade. Like anything else, it's fine within it's capability.

I have an original manual for mine, it calls the spindle taper out as a #30 MMT, which it defines elsewhere as "Milling Machine Taper". I don't know what the modern equivalent is, but I recall making note of info someplace that gives the "modern" designation. I'll see if I can find it. I also think that most of the modern toolholders may lack the 2 "pockets" in the taper that the SB mill uses to hold the toolholder in the spindle. Not to state the obvious, but you could likely measure what you have and compare to the published outlines for the NMTB taper. You may have to add the pockets, but I don't imagine they would need to be super precise.

This page indicates that the NMTB taper is also called a "MM" taper:

http://www.timgoldstein.com/cad_cam/tapers.htm

Scroll down to "single flange tapers" and read...

I have 2 collet holders, the shell mill holder and the original accessory boring head (Made by Flynn Machine & tool and still available) so have never really needed to hunt down additional holders.

I think I have a scanned copy of the manual, if you would like a copy. It includes parts lists and some exploded views of the various assemblies. I could post someplace for download, or email it to you, if you wish.

-Al A.

[BMSS]

I went out and took a couple of pictures of the mill and its toolholders. I can't post here, but you can see the pictures at: http://s552.photobucket.com/albums/j...ool%20holders/

It appears to me that the original motor was removed, and replaced with a single phase motor. When that was done, the drawbar could no longer be used. (I have the original motor, the previous owner sent it with the mill.)
I think that is when they started using this locking system.

Thanks for the suggestions Al & Paul, I will have to do some more reading.

[alanganes]

No, they came that way from the factory and they are shown as such in the original manuals. They never had a drawbar setup, as the motor sat directly above the quill.
Mine has the original pancake motor, I run it off of a VFD. My spindle is set up the same as your, with the 2 set screws. Your toolholders look to have been modified from standard units.

Late addition:

I just found the link to this post from PM that I had saved. It should answer some of your questions with respect to the toolholders, and shows how one guy modified some modern units for use on this machine:

http://www.practicalmachinist.com/vb/showthread.php?t=153209&highlight=ER40+collet+chuck

-Al A.

[BMSS]

Thanks Alan, that answers all my questions. I appreciate the help.

Bob Denton

[alanganes]

You are most welcome. Glad I can help out.

If you would like a copy of the manual, I found my scanned copy. It is a quite large, 3 PDF's, about 6megs each. I can email them, or find someplace to post them for download. They are good clear scans that I did myself from my manual and parts list.

Enjoy the mill, I like mine!

-Al A.

[BMSS]

Alan, I would like to have a scanned copy of that manual.
You can e-mail it to me at;
[email protected]

Again, Thanks for all the help.

Bob Denton

[oldtiffie]

NMTP tapers

Paul,

these pics/scans should help in regard to the NMTP tapers - including 30:

http://i200.photobucket.com/albums/aa294/oldtiffie/machine_tapers/Machine-taper5.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Machinery_HB27/NMTP_tapers1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Machinery_HB27/NMTP_tapers2.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Machinery_HB27/NMTP_tapers3.jpg

[pcarpenter]

Your photo seems to show some holders I have seen before...and never understood. I do now. Other than the grooves ground in for retention, the holders look like the 30 national holders I have. With that in mind, it really is possible that the reason they look hand ground is that someone took a standard holder and put the retention grooves in it with an angle grinder or something. They sure are deep!

In any case, I will bet that will point you in the right direction. There should be some used 30 National (NMTB) stuff out there and I know you can get some import items as well although the 40 National is more common.

Paul

[Fasttrack]

I'd like to see some pics of the mill, if you've got the time. I'm amassing a collection of mill photographs. Sort of like my own, personal version of Tony's Lathes.co.uk site.

[tiptop]

It looks like a strange way of securing a 30 taper. One thing that comes to mind is without the same torque on your retention screws, it will work in the taper. The NMTB tapers are far superior to R8 tapers, this can be seen in the contact area of the taper. They are very rigid they can be found in 20, 25, 30, 35, 40, 50 and 60 series. I would also like to see a picture of your mill. I have looked at them in the past but don't remember them not having a drawbar. Old age is great. There is a lot of used NMTB stuff out there, but NMTB 40 and NMTB 50 seem to be the most common as this was most prevelant in industry. I run NMTB 30 in my mill with a drawbar and am very happy with it.

Jay

[alanganes]

It is a bit strange, and after having one for a while, it's obvious why this system never caught on. It works well enough though, I've never had a hint of anything working loose. Just a bit of pressure on the screws seats the tool in there very securely, I guess due to the large taper contact area.

Not real fast for tool changes, but I mostly use the collet holder anyhow, and have all of the collets that it originally came with. And I'm not in much of a hurry.

Perhaps it is the presence of those two pockets that makes this a "milling machine" taper rather than an NMTB. It seems to be identical otherwise. I have never see one used on any other machine, but I don't get out much, either.

Here is a picture of mine:



Not a great view for what we are discussing here, but you can almost see that the motor is mounted directly above the quill. The motor is only about 6" high. These mills used a Fairbanks-Morse or GE "pancake" motor, which is very short and fat compared to modern motors. It was available with either a 3/4 HP or 1 HP motor, and either could be ordered in single or 3 phase. Mine is the 3PH, 1HP unit, I run it with a VFD.

All in all it is a decent mill for my purposes.

I can get a few better angles if anyone cares to see.

[BMSS]

Alan & Fasttrack
Sorry it has taken me awhile to get back to my post. I had to go out and take some pictures. I can't post here, but you can see my mill at;

http://s552.photobucket.com/albums/jj353/BMSS_photos/Mill%20tool%20holders/

As you can see in the photos, I have added a "poor man's DRO" to my mill. The system works great for me. Enjoy the photos

BMSS

[tiptop]

The tool holders look just like a modified NMTB 30 taper tool holder. I suppose it would work alright as you all have stated that it does. It is unfortunate that you are not able to have a set of drive dogs in the tool holder slots which look to me to be hidden from the quill by the attachment system. This is one of the nice things about NMTB series holders, you not only have a very large taper contact area but the drive dogs also. Then as I am sure you are aware of it being a faster tool change with a draw bar or draw bolt. It is to bad they did not put a hole through the motor spindle for a long allen wrench to tighten a draw bolt. That is kind of what they did on the Frays. Th S.B. millers are nice looking HSM machines, just a little smaller that my Fray on travels.

Jay