Replacement Spindle for benchtop milling machine

[magicniner]

Given that they were a perfectly adequate machine I'd repair the existing spindle.
On my benchtop mill I have a 10mm EasyChange Endmill holder and a 12mm EasyChange Endmill holder and use ER11 collet chucks on 10mm shanks and ER16 collet chucks on 12mm shanks as tool holders, this gives really quick tool changes and the collet chucks are cheap so it's affordable to have a rack full with tooling loaded.
Check the manufacturer's spec for the spindle bearings, I got rid of a DC motor that ran to 4000rpm and replaced it with a 3 Phase that runs to 7000 without issues.

- Nick

[Rabs]

Given that they were a perfectly adequate machine I'd repair the existing spindle.
On my benchtop mill I have a 10mm EasyChange Endmill holder and a 12mm EasyChange Endmill holder and use ER11 collet chucks on 10mm shanks and ER16 collet chucks on 12mm shanks as tool holders, this gives really quick tool changes and the collet chucks are cheap so it's affordable to have a rack full with tooling loaded.
Check the manufacturer's spec for the spindle bearings, I got rid of a DC motor that ran to 4000rpm and replaced it with a 3 Phase that runs to 7000 without issues.

- Nick

Hi Nick,
Thanks for replying. Have you got the same machine? I suspect that we must have slightly different setups. If I did as you do with tool->ER collet chuck with straight shank->easychange holder-> easychange chuck-> spindle the tool would be so far out that I wouldn't have much z travel left, not to mention losing a load of stiffness.

I like the idea of reusing the spindle but I'm really not sure that either it or I am up to it. In addition to the slop in the bearings there is also a load of runout (~0.1mm). I suspect that it was badly crashed at some point and then 'repaired'. The holes for the face pin spanner look like they've been badly abused. I have managed to get it apart but it was a complete pain so I'll need to machine a new one. I don't have any certainty that the spindle itself isn't damaged as well as the bearings.

I don't have an internal bearing pullers or a press to reassemble the spindle with new ones. I also don't have a huge amount of time to invest in the project and need the machine working fairly soon so I am looking for a more 'off the shelf' solution.

[magicniner]

I'd be really surprised if you couldn't get a local engineering company to do the press work for you.
My little benchtop mill is based on the Connect Contour, the smaller model than yours I think.
A 10mm Endmill holder gives me 8 1/2" Z clearance, ER11 collet chucks on short 10mm shanks take 1" of that, then add the cutter protrusion of choice.
I've profile cut stainless parts 12mm deep from solid with 6mm single and 2 flute cutters in an ER11 in the 10mm endmill holder, it's not fast but it does it and tool life is OK.


I'm in the process of machining a column to take an Emco milling head for a friend, he has a high speed spindle and it doesn't come down to low enough speeds with high enough torque to do much of what he wants,

- Nick

[Rabs]

I'd be really surprised if you couldn't get a local engineering company to do the press work for you.

I'm sure you are right but that's not the route I want to go down. It would take a lot of my time (and probably quite a bit of money) to extract all the parts, source replacements, find someone to reassemble it, take it to them and then hope (with no guarantee) that it works and runs true when it get it all back together. Once I've factored in the cost of this and the 2 or 3 easychange holders I'd need to buy it's going to be more expensive than any of the replacement spindles I'm looking at. So, as I say, I'm not going to try to repair what is there at the moment.

I'm in the process of machining a column to take an Emco milling head for a friend, he has a high speed spindle and it doesn't come down to low enough speeds with high enough torque to do much of what he wants,
- Nick

That's interesting. Do you know where he got the milling head? Does someone sell them as spares? One of the problems with my list is that most of them are coming from overseas, so if there is a UK supplier of spare parts for a suitable mill then that might be a good option.


Thanks for your help

[magicniner]

That's interesting. Do you know where he got the milling head? Does someone sell them as spares? One of the problems with my list is that most of them are coming from overseas, so if there is a UK supplier of spare parts for a suitable mill then that might be a good option.

I don't think it would work for you, it's small and you'd have no-where to mount a motor, it's not an "off the shelf" solution.

My suggestions were all aimed at getting it up and running as quickly as possible with the least cost and the best overall machining capacity.
Buy a spindle that fits where the old quill went and live with the speeds/torque/tool capacity you get but don't throw away the old bits, they will enhance the resale value,

- Nick

[m_c]

Are the original bearings noisy?
If they're not noisy, I'd try adjusting them up, and then test it again. Even if you just tighten the one ring to remove play, it'll give you a far better idea of what condition the spindle is in.

As for potential replacements, it'll depend on the space available. Do you have any photos of the existing head?
Personally, I'd be looking at something that makes tool changes reasonably easy, like a BT spindle, so you can swap tools without having to worry about setting tool lengths.