PR Z Upgrade: Inside The Z Carriage Or Outside?

[rb99]

I am installing the new Z on my old PR and I used to have 2 Z's on it before. The struts that the Z bolts to are longer than the Y rails so they overhang on one side of the Y. This will allow me to have the Z on the outside of the Y rail, or I can have the Z between the two Y rails.

I find it difficult to access the router to change bits etc. when it is tucked in between the two Y rails. I think it would be easier to change bits if the router is hanging over the outside of the Y. I would want the side the Y motor is on to be the side the router is on so the weight is at the Y motor, not across from it. This will require me to flip the Y carriage 180 degrees, and then fiddle with the Z rails to change which end the strut hangs over.

So is it worth it?

I am going to use the Kent dust foot, and perhaps the clear Shopbot foot, as well as a homemade one that does not attach to the router.

Any thoughts on this router placement?

Thanks for reading!

[Brady Watson]

Normally you cannot get 2 routers in the bay. Both Zs are spread way out to make room. You can get 1 PC 3.5hp and a drill or Colt router - but not two full sized PCs. You can also get two 3hp Colombo spindles in there, (on a PRT) but it's real tight.

You really have to watch running 2 Zs on that gantry. You're 'rollin heavy' and a dial indicator will show the sag in the middle...

-B

[rb99]

Normally you cannot get 2 routers in the bay. Both Zs are spread way out to make room. You can get 1 PC 3.5hp and a drill or Colt router - but not two full sized PCs. You can also get two 3hp Colombo spindles in there, (on a PRT) but it's real tight.

You really have to watch running 2 Zs on that gantry. You're 'rollin heavy' and a dial indicator will show the sag in the middle...

-B

Thanks Brady. I am not looking to run 2 Z's, only one. But I am wondering about running it outside one rail, as opposed in between the two. This makes accessing the router 1,000,000 times easier.

It does put most of the weight on the one side though. If I did it, I would try to add a couple of more V bearings on the Z carriage that is carrying the weight.

I have added some substantial angle iron to beef up the Z and Y rails.

What style of dial indicator do you recommend for doing these types of measurements?

Thank you!

[Brady Watson]

I usually park the tool @ 12,12 to make tool changes easy on PRTs. I would imagine that PRs would be similar. This keeps the bit from dropping on the floor and allows you to access the router by laying your elbows on the Y0 side of the gantry and change the bit that way.

Having the router cantilevered off the gantry isn't ideal - because you'll lose some X travel. If you absolutely have to do it this way, add a regular old ball bearing (say 1" in da) with a spring arm to the opposite side of the Y rack gear to keep that side of the gantry firmly planted. I don't have a PR in front of me to remember the exact config of the bearings...but I think you get the general idea.

The table should be machined flat first - because it can be WAY out when it sits for a while or was freshly glued down. Any dial indicator is fine - get one with a magnetic base and stick it to the steel. HF sells them - Grizzly etc. It doesn't need to be fancy. $20-30 US will get you one with .001 accuracy.

-B