Another PM-833TV thread!

[Juanca]

Hello M.T. Pockets,
It has been practically one year since you got your PM 833 TV. Hope that you have enjoy it very much as I do mine. I have made a couple of "improvements" to mine that would like to share with you. One is regarding the measurement of the spindle travel and the other, that I consider most significant i the design and built a "Spindle Lock Mechanism" that facilitated the job of changing tools.

 

[M.T. Pockets]

Interesting mod Juanca, how does the spindle lock actually lock? It looks like it grabs one of the ribs on the spline shaft?

 

[Juanca]

Hello M.T.Pockets. Yes that is exactly what it does. The "plunge" get into the spline of the spindle shaft. Quite simple but very effective. It is so much friendly at the time of changing from one tool to an other, specially when you are doing a work that requires several different tools.

 

[M.T. Pockets]

Quick update on some mods.

First, I installed power feed on the x-axis. I went the ebay route instead of buying the more expensive option at PM and now I realize why the PM unit is so much more expensive. This thing was a real PITA to install. I had to do a bunch of cutting and milling on the drive unit itself and modify the casted aluminum bracket that comes with it. It took me about four hours to install the thing but it works quite well.

Second, I replaced the stock 6002Z deep groove bearings on the x and y handles with some ABEC#5 7002AC angular contact bearings. The deep groove bearings aren't really designed for the preload needed which makes them feel very lumpy and crunchy when rotating the handles. With the angular contact bearings the handles now rotate very smoothly and it feels like the old bridgeports I used in uni. Although my machine still has ~7 thou of backlash and those has essentially none... The leadscrew nuts will be the next modification.

Here is the link to the bearings I purchased: https://www.bocabearings.com/products/7002-2rs-5-rpg-21610
The 833 requires 2 bearings per axis.

Also, I need some sort of way cover for the front of the y-axis. Anyone found a good way cover that fits this mill and doesn't get in the way of the y-axis crank?

 

[7milesup]

I too have been pondering a Y axis way cover. I was thinking about some Buna-N just like the stuff on the Z axis. Let it hang over the front?

 

[M.T. Pockets]

I too have been pondering a Y axis way cover. I was thinking about some Buna-N just like the stuff on the Z axis. Let it hang over the front?

You could but then it would get in the way of the y-axis handle. Maybe just put a guard up or something to keep it out the way? I dunno...

 

[7milesup]

I was thinking it would just "waterfall" over the front. The thinner the material the better maybe...

 

[Tipton1965]

The leadscrew nuts will be the next modification.

Have you found a good replacement for the leadscrew nuts?

 

[M.T. Pockets]

A couple possibilities but haven't pulled the trigger on anything yet. I've found some plane jane 1"-10 acme bronze nuts on McMaster and a couple other places but what I'd really like is something made from Acetal with blacklash adjustment.

 

[davidpbest]

I too have been pondering a Y axis way cover. I was thinking about some Buna-N just like the stuff on the Z axis. Let it hang over the front?

Go to 14:40 in this video. REAL men use leather. Found mine on eBay.