Thread: NT30 spindle vendor for RF45 mills?

Ewan, now you are getting into difficult stuff. Bolts are torqued to take them into their elastic deformation range so that the (elastically) stretched bolt will act as a bit of a spring and hold itself in. Different grades of bolt have different yield strengths and so have different torques to get them to the percentage of yield that the design specifies. The figure that is typically aimed for is 65% of yield.
The relevance to this discussion is that typically the torque required on say a M16 drawbar should be the same torque required for a M16 bolt of the same grade. The trouble with 'just nipping them up' is that if it is not enough then the drawbar can loosen in the arbor with the possibility that the arbor comes loose. I usually do up a drawbar until it is 'firm' (that is, stopping short of eyeball popping torques). Ideally if you wanted to lessen the torque needed on a drawbar then something with a lower elastic deformation is needed. Perhaps something to try would be a few disc washers - enough to get some compression on the stack so the arbor is held into the socket with a bit of spring but not as tight as it would be by tensioning a draw bar. Too little spring though and the cutter may chatter around as the flutes may want to pull it out of the socket.

Another thought - check that both the taper and socket are oil free. The self releasing bit is based on the friction angle for dry steel on steel. If there is some oil there it changes the coefficient of friction and may make things stick more.

Michael

Just reading Michael post and remembering what I said earlier in the thread I thought I would add to it so I don't give the wrong impression to members about tightening the draw bar.

My mill is usually in the lower rang around 400rpm as I do mostly steel, at this lower range the spindle has a good resistance to turning so a good thump with the palm of your hand is tight enough.
If it's in the higher ranges it need a spindle spanner which is why I made one.

Every time I need to get it out it always takes a firm tap with the open ended spanner I use for tightening it. There are some nice spindle spanner/hammer combination tools made up by some members which is another way to go.

Here is the spindle spanner I am talking about, if some members are getting a NT30 spindle this will come in handy if you don't have a spindle lock.
https://www.woodworkforums.com/f65/nt...panner-121506/

Dave

Originally Posted by Dave J

There are some nice spindle spanner/hammer combination tools made up by some members which is another way to go.

Here is the one I made, originally for my X2 Mill drawbar, but it also fits my DM45 drawbar for the R8 spindle

Gotta be lucky sometimes!

https://www.woodworkforums.com/f65/co...r-tool-108330/

I thought it was you Fred, but wasn't 100% sure.
Nice job you did on that



Dave

Originally Posted by Michael G

Ewan, now you are getting into difficult stuff. Bolts are torqued to take them into their elastic deformation range so that the (elastically) stretched bolt will act as a bit of a spring and hold itself in. Different grades of bolt have different yield strengths and so have different torques to get them to the percentage of yield that the design specifies. The figure that is typically aimed for is 65% of yield.
The relevance to this discussion is that typically the torque required on say a M16 drawbar should be the same torque required for a M16 bolt of the same grade. The trouble with 'just nipping them up' is that if it is not enough then the drawbar can loosen in the arbor with the possibility that the arbor comes loose. I usually do up a drawbar until it is 'firm' (that is, stopping short of eyeball popping torques). Ideally if you wanted to lessen the torque needed on a drawbar then something with a lower elastic deformation is needed. Perhaps something to try would be a few disc washers - enough to get some compression on the stack so the arbor is held into the socket with a bit of spring but not as tight as it would be by tensioning a draw bar. Too little spring though and the cutter may chatter around as the flutes may want to pull it out of the socket.

Another thought - check that both the taper and socket are oil free. The self releasing bit is based on the friction angle for dry steel on steel. If there is some oil there it changes the coefficient of friction and may make things stick more.

Michael

Hi Michael,
Thanks for the explanation. Firstly, my tapers are clean and dry. I was lucky that there was a tool in both the vertical and horizontal for the time she was sitting so the tapers are perfect, no pitting or rust etc.

I had another tighten/loosen after reading this earlier, an there is no way i would consider that i'm over tightening. I am doing it up more than the 30 taper, but a, i'm using a longer spanner, and b, the machine offers a fair bit mare resistance to spinning than the HM50, how much depends of course on what gear she's in. I certainly havn't had any signs of being too loose, i have had the taper come loose on the HM50 many years ago and know what it sounds and feels like.....

Now the Mars is running again i actually stated making 2 metric drawbars. The 2 that were with here are both imperial, and of course all the tooling i have bought is metric. I have been using just some threaded rod, this may also be adding to my problems if it is not exactly central on the spindle bore.

Cheers,
Ewan

Re the address link given for the Iso spindle. I have emailed these guys twice since making the last post here.
I don't know if they are just averse to answering emails or I am doing it wrong as it requires a form of job ticket.
The site says an email giving the job ticket no will be sent back to the enquirer,but nothing has turned up so far.

In case any one was hanging out for an answer.Feel free to email yourself, your luck may be better..

Grahame

Well thats no good at all Grahame, been there myself not long ago looking for some DTI's.
Does the "tick status" show anything useful?

Stuart

I don't know about any tick. I am not giving them one. It appeared that I might need to register to be at least recognised.

That wasn't possible either as Australia wasn't listed in the pulldown box selection. Maybe it was no registration,no reply, I dunno?

Customers from only select countries perhaps?

Maybe the Canucks don't like Aussies??

Grahame

Sorry Grahame,
"ticket" status,
MTW :: Support Ticket System

But its just dawned on me, if you didnt get an email with a ticket number, that will make it a little tricky to check the status of your ticket.

Stuart