Strange R8 Collet Problem.

[ARKnack]

I have had to remill a few keyway slots on R8 collets through the years because of not fitting. The slots seemed to be the most common problem. I have also had to replace a few thread inserts in a few because they were case hardened which caused the threads to become tight and caused the threads on the drawbar to gall and strip. I usually try the drawbar in all new collets before even tying then in a machine. If tight I check to see if it has a threaded insert that can be changed (usually only the better r8 collets have the inserts ). The next thing is how it fits into the spindle. Sometimes I will use some bluing to see where it is binding before I go further.

Actually, my mill doesn't even have a key for the keyway. Somebody in the past removed it. I remember reading that removing the collet key was a common practice with machinist. I haven't had any problems with out the key.

 

[Billh50]

I only had the problem once of a draw bar galling. But it was enough to make me leave the key in. Took me a while to figure out how to get the galled up drawbar out when the collet kept spinning. I do know how to get them out easily now but just don't want to take the chance.

 

[rdsii64]

I called littlemachineshop.com today and explained my problem. It seems that Sieg ( the company who actually makes the X2 mini mill) had a bad run of mills with this very problem. A Sieg rep had to replace the spindles in LMS's current stock of mills. They issued me an RMA for a new spindle. When I told them I didn't have access to a hydrolic press, they said they would to ship me out a complete head less the motor. All I have to do is swap heads, put my motor and belt drive kit on the new head. I'm now just waiting for the rep to email or call me with who is shipping first. Hopefully they will ship me the new head first so I can use the same shipping box for the return trip. The rep I talked to on the phone is pretty sure the problem is not with my collets. Having to dismantle my mill is kind of a bummer but at least the company is making it right. The bright side is I will VERY WELL AQUAINTED with my mill when this is all said and done.

 

[timbertoes]

Not sure I understand what the problem is 100% - however I will add:
I have had several R8 collets whose keyway was not long enough. collet would come up short in the spindle. Milled the collet keyway longer, and the collet fit correctly.

 

[RJSakowski]

Not sure I understand what the problem is 100% - however I will add:
I have had several R8 collets whose keyway was not long enough. collet would come up short in the spindle. Milled the collet keyway longer, and the collet fit correctly.

I just checked my two machines. On the mill/drill I hit the bottom of the key at 1.5" above the face of the spindle; on the Tormach it is 2.3 above the face of the spindle. As I said earlier, It is my understanding that the R8 collet system is an internal Bridgeport standard and different manufacturers came up with their own specs.

 

[Doubleeboy]

I have a several Lyndex collets for my mill R8. They are fine, fit the keyway, taper and threads of drawbar fine. I bought a full set of collets from one of the China suppliers, and they fit dreadfully, returned them and bought the Enco branded set, they do not fit quite as well as the Lyndex but they are usable and accurate and way cheaper. One good practice is to blow out your collet threads from time to time, clean the threads on the drawbar and put a drop of oil on the threads every once in a while. I know a chap who runs a pretty large shop and every January every mill gets a new drawbar and old ones are scrapped, saves them time, money and frustration. Based on his example, I replace my draw bar every five years and each time I have done it I have smiled realizing that using my mill is now easier than it was a week earlier. Dorian drawbars only for me, no imports.

michael

 

[rdsii64]

Today after I got back home from taking my wife to her appointment, I took the motor, belt, and drive pulley, off my head. I boxed it up and shipped it back to Littlemachineshop.com. They are going to replace my spindle, and ship the head back to me. Shipping both ways is on their dime as well. After it arrives I'll call them and try to get a general time frame for how long this should take. I hope I get lucky and they just ship me a new head. I forgot to take the driven pulley off the spindle so I ordered a second driven pulley just in case they ship me a new head and forget to take the driven pulley off the old one.

 

[1tcoffman]

I have a very weird problem with my mill. When ever I have to remove or reinstall my R8 shank drill chuck, it goes off with out a hitch. All I have to do is lossen the draw bar a half turn, give a light tap with a hammer or rubber mallet, then back out the draw bar and easy peasy its done. I actually have to hold my hand under it to catch it when it falls out. Its that easy.

My R8 collets are another affair. Installing a removing an R8 is such a fight I have actually galled the threads on my draw bar and had to replace it. Inf fact I actually have to tap the collet up into the spindal so the draw bar can thread into it. I know this can't be right I just don't why, nore how to fix it.

If it will help figure out the problem, my mill is your typical bench top X2 mini mill with an air spring and belt drive conversion.

I have considered just going to end mill holders and swearing off collets for good but I'm not sure I won't hve this issue with an end mill holder.

Please advise

I had the same problem when I got my HF mill last winter. It happened with the very first collet I had at the time. After going through all the channels on the internet, I finally just looked at the collet and noted where it it was shiny and scarred. Used some fine wet or dry sandpaper until it worked. I've never had the problem with the other 2 collets I bought, so it must be a manufacturing problem.

 

[rdsii64]

Got a call from littlemachineshop.com today before I left work. They got my mill head today and the rep I spoke to said the spindle would be replace today and should go out in todays mail on its way back to me. Since I have a belt drive conversion kit, they removed the internal plastic gears for free. It was a bummer to have to dismantle my mill but the company made it right and their customer service was top notch. When I get my milll head back and my modulus arms jig is delivered my projects can resume.

 

[higgite]

rdsii64,

I've been eyeballing a LMS mini mill, just haven't pulled the trigger, yet. So, this thread has been very informative for me. I already knew from experience that LMS customer service is top notch, but have gleaned some valuable knowledge about collets/spindles/keys/keyways without the inconvenience that you have experienced. Thanks for posting and thanks to those who reponded.

Tom