Bridgeport tooling - MT3 v R-8

Beginner question here. Note that I own some machine tools but still haven't had a chance to start using them! So don't assume I have any
commonly understood machinist knowledge cause I ain't one. Yet.
I've got an old, very well used, BP that I was going to rebuild but had a chance to score a lightly used BP J-head Series 1 so now I've got two. The one I just bought is set up for MT3 tooling. Can I use this as is or should I change out whatever parts in the spindle to make it use R-8 tooling.? What parts might be involved? The old BP is pretty worn so I don't want to swap heads or take parts out for the new one.
Thanks. Steve.
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I wouldn't try taking a BP spindle apart. The bearings are pre loaded and possibly need special tools to dismantle and reassemble.
Roy SteveF wrote:

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snipped-for-privacy@rtpmep.co.uk says...

The J-head spindles are quite straightforward to work on. Preload is predetermined by the bearing set. The proper hook spanner and pin spanner are nice to have, but by no means necessary.
I understand that the M-heads are another matter entirely.
Ned Simmons
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SteveF wrote:

MT3? Really? I didn't know BP ever had a head that used MT3. I know of BS9, MT2 and R8.
It wouldn't be the first time I learned something new from this group....
JW
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wrote:

Based on several years of working in an academic/training environment with millling machines with both R8 and MT spindles, I doubt you will find and any operational difference for the typical home shop machinist, although there is always the "real machinists/milling machines use R8 collets" factor.
To be sure, the R8 spindle with R8 collets and holders can hold much larger tooling than can the 3MT, but the much larger tooling is also much more expensive and in general is better suited to a production environment.
The downside with using drawbar MT collets is that the MT is a self holding taper, and it can be difficult/time consuming to change collets/tooling.
Given that you will most likely be buying collets, I suggest that you purchase a 3MT holder using ER collets. I have found the ER collet end mill holders to be both very rigid and easy/quick to change. You will not need the complete collet set, as end mills and other tools have more or less standardized on 3/8 and 1/2 diameter shanks, at least in the U.S. The down-side is the MT/ER holders do extend 2 to 3 inches from the spindle slightly reducing clearance.
An alternative is MT shank end mill holders which use a set-screw to retain "Weldon" style shank end mills and tools. I have found that it is easy to file or grind a "Weldon" style flat on tooling not so equiped, and items such as edge finders and wigglers work fine with only light clamping pressure from the setscrew as there is no significant torque required during operation.
I have extensively used both styles and found them very satisfactory, although my personal preference is for the ER collet type.
for examples of the ER style holders see: http://tool-holder.electronic.com.tw/collet-chuck-for-ER/MTB2-MTB3-MTB4-MTB5.htm http://www.hhip.com/products/product_view.php?ProductID 0-0005-061
for examples of the set-screw style holders see: http://www.use-enco.com/CGI/INPDFF?PMPAGE02 http://phase2plus.com/details.asp?pr=MORSE_TAPER_END_MILL_ADAPTORS&idC http://www.wttool.com/c/16080005p
For the very occasional times when spindle/table clearance might be a problem, 3MT drawbar collets are available which either do not extend past the end of the spindle or do so only minimally.
Uncle George
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Correction - The machine has a Fast Change 30 which is an NMTB 30 without the drawbar.
Steve.
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    [ ... ]

    [ ... ]

    Aha! This makes more sense with the Series-I machine.
    You'll need to find the 30 NMTB end mill holders, and collet holders, but those should be excellent for your work. I would not bother changing to an R8 spindle. Among other things, if you eventually convert the machine to CNC, the quick-change tools with preset tool offsets per tool will make the CNC a lot easier to live with.
    You can find them on eBay. You can buy one or two *new* from someplace like MSC, to get yourself started -- say a 1/2" end mill holder and a 3/8" end mill holder, and then look for the others on eBay, or at used tool dealers, if you have any near where you live.
    I can even use my 30 taper tooling in my Nichols horizontal mill (40 taper spindle), with an adaptor sleeve from 30 taper to 40 taper, and a homemade drawbar to fit the different thread.
    Enjoy,         DoN.
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