Additional Z axis clearance

[cip]

Does anyone have any ideas on getting more Z axis clearance.

[Brady Watson]

How much are you looking for?

Here's (http://www.bradywatson.com/) what I did. I added a 1/4" wall 2X3 & I get an additional 2" of clearance with a stock PRT gantry. More than that & you really have to watch for deflection.

This is the perfect amount of rise to clear a 6" indexer chuck.

-Brady

[cip]

Thanks brady, I have a 2 week old alpha 60 X 144 and can already see that there is not enough Z clearance. I was thinking of putting a 2" X 3" block under each corner of the Y gantry. Do you think that deflection will be a problem using this procedure?

Mike

[Brady Watson]

Mike,
I am not sure that the 2X3 will work on an Alpha since the 'bulkheads' where the extrusions meet the steel are different than a PRT.

You *may* experience some issues with deflection depending on what you are cutting & dialing in the Z-axis perfectly becomes more critical.

-Brady

[davidallen]

You could try lowering the table.

[cip]

David,
That's an option I had not thought of. And now would be the time before I get the Vacuum piped in.

Mike

[marshawk]

Mike, I just put the Z Axis brackets on the top side of the cross brace. Rather than explain it better, you can see pictures of it at: http://marshallsmillwork.com/shop.htm

The shorter bits fon't quite reach the table so we made a removable table for thicker projects.

Cheers!, Chip

[Brady Watson]

Chip,
That won't work on an Alpha since there are no brackets anymore...The Z-axis bolts directly to the AL extrusions.

Not to let your pics go to waste, another way would be to raise the rails up...although I am not a huge fan of the idea using pipes. If I were doing it, I would just lay a piece of 2X2 or 2X3 under the rails and use longer bolts. I like the idea of bridging the gaps under the rails with solid material rather than making the rails bridge the gap with no support in between bolts.

-Brady

[marshawk]

Thanks Brady, I skipped right over the "Alpha" part...

Actually, I was skeptical about the pipe too, but it is rock solid. We have had it that way for about 2 years now. We have the bolts tight enough to where they don't warp the rails, but hold them tight. Works good...

I didn't think about that mod when I typed my last post. They work fine with our small PRT, but I do not know how it would work with the added weight of the Alpha.

[Brady Watson]

The Aplha and now new PRT uses a completely different gantry than the ones you and I have. The gantry is actually a bit lighter than the ones we have too.

-B

[marshawk]

Really? I have only seen pictures of one and the whole setup looks heavier.

Huh...go figure...

[joel_schuman]

I haven't seen any numbers in this thread. My table is a PRT 120, Colombo spindle, 3/4" ply support base, 3/4" MDF plenum. new 3/4" MDF spoil/bleeder board. As delivered, the collet face bottomed at 1-7/8" below the bleeder board surface, and raised to 5-1/2". Could thru-cut material ~2-5/8" max. Raising the Y rails 3" gives a max collet hieght of 8-1/2", making 4-1/8" material possible. The low collet height is now 1-1/8" above the table. So far it's a winner.