BT32 - Z tracking problems

[GeneMpls]

I bought a BT32 used and it looks like new... but the more I get to know
the machine the more problems I see. I noticed that the rails and V rollers
were a bit rusty and cleaned them up as well as I could; noticed that the
Z had a couple of 'hitches' in it as it traversed up and down and that one
of the left side (upper, outer) facing the router motor rollers was not making
good contact... I figured I needed to adjust it. I have done my homework
reading as many posts on this fine forum as possible so I pulled the Z
motor and counted the teeth on the pinion and ordered one so when I
pulled the Z apart I could have everything needed.

With the motor out I can hardly move the Z up and down at all. Not good.
So I looked at the Z roller adjustments and you can only adjust the right
hand upper and lower (inside and outside separately) rollers- no adjust on
the left side at all. I have looked thru the manual and I assume that the
Z comes already assembled so it is really not mentioned. I don't see a
way to adjust the upper outer left V roller. I am thinking that after taking
the router motor and springs off- I could roll the assembly off the tracks
upward but I cannot find the stop either. Any thoughts? Thanks Gene

[garyc]

Gene...
There are a few different models of the BT. Can you post a pic of the front (up position) and rear of the Z (in the down position) and we can give you some steps to adjust/repair.

[GeneMpls]

Here ya go- kinda hard to take a decent pict of the rear the way the machine
is positioned so I hope this will work. I have your ' adjusting the z bearings
on a PRS pdf but that is obviously a newer design. Thanks Gene

BTW- it would be useful for us plebes if there was a chronology of the different
models and updates to them. Does something like that exist? I have studied
a lot of picts but I is difficult to orient oneself. I ordered a Z pinion and was
almost sent the 25 tooth one (which is apparently on the build sheet)-
fortunately I had seen a post recommending counting the teeth. I should also
have mentioned it is a BT32 standard- and a preowned machine- could have
been changed for a speed advantage?

[garyc]

Gene...

Your machine is a Gen1 PRS

Your questions,mostly in order. :rolleyes:

There is no chronological publication. Keeping up with the constant improvements and changes would be a task I wouldn't want.

Yes, the 20 tooth is correct for a standard on the Z, but it is always prudent to count, especially with a used machine. Going to a 25 would increase your speed by 20%. That speed is not needed on the Z axis. The resulting decrease in power would be a detriment.


Since you know that there is a problem with the Z motion, I would dissassemble it completely and check for the following:

All parts are clean, shiny, etc
All bearings roll freely
That the eccentrics turn freely
That the dual v rails on each side are parallel with the extrusion. Do this by using a surface plate or a table saw/jointer cast bed and feeler gauges.
That the rollers contact the V rails uniformly

Lube and reassemble, adjust the eccectric side for smooth motion.

More info here from Archives circa 2007: http://www.talkshopbot.com/forum/showthread.php?t=2605&highlight=tune

[GeneMpls]

There is no chronological publication. Keeping up with the constant improvements and changes would be a task I wouldn't want.

I believe this... but even an imperfect list that was updated as questions
came up would be a step forward. If you are the original owner you can
kind of keep up but for us 2nd (and 3rd) owners it is hard. And you have
a lot of history out there as the older machines are trading hands.
For instance I have a lot of time invested figuring out that I have the 4G
board and it is considered a PRS and that there are 2 distinct styles (even
the website has pictures of both interspersed) etc. Just a thought.

It looks like the Z extrusion can only come out the bottom as that is the only
stop bolt that is accessible- correct? Thanks

[garyc]

Gene...
I cant answer that one for sure, but there should be a stop bolt on both ends of the travel. Not sure if both are accessable when on the machine.

[GeneMpls]

Just for future reference- it does come out the bottom only. I now have all
motors loose and the table off- checking everything. I don't have time to
actually use it during the week but I can sneak off and putz with it now and
then when no one is looking. Thanks Gene

[GeneMpls]

OK- I took the Z apart (and the table off) and cleaned everything up and
greased and everything is *smooth*. Now the router falls of it's own
weight when the machine is turned off? Is that right? It always stayed where
I left it before (very tight). Thanks Gene

[garyc]

Gene...
Were there 2 springs that counterbalance the weight of the Z? If not you can order them from SB. If they are there, you should be able to get some heavier ones.