G0704 Head Spacer Modification

[MikeSherman]

I thought I'd share my version of the G0704 head spacer modification. I use this spacer in conjunction with the spacer block that gets bolted to the base to column joint.

I decided to go with a 7-piece fabrication instead of hogging out an expensive block of aluminum. The finished spacer only weighs 3.2lbs, spaces the head 2.50" further out and looks pretty cool too! It permanently bolts to the spindle head with (6) M6 SHCS. It still retains the 4-bolt fastening scheme around the head pivot. I support the 3-bolt main t-bolts via spacers between the flat plates so there isn't any deflection as the bolt are drawn tight. The center bolt isn't supported so I use it simply add tension while tramming and to keep the head from coming off.

I removed the set screw on the side which originally kept the head form physically coming off the base plate - I felt it wasn't necessary. I added a 3/8 slot at 12 o'clock for a bolt to aid in pulling the head tight against the base plate. The slot still offers +/- head rotation of 12deg. Any more than that simply remove the bolt.

Here are some pics:

CAD:



Finished Assy:



Installed:




If anyone is interested in having one (for a fee), just PM me.

Thanks!

Mike

Similar Threads:

• Need Help!- G0704 Removing Head
• The X2 head spacer design thread
• Bridgeport head modification for CNC
• What is a good indexing head/super spacer to convert to 4th axis?
• IH mill head spacer

[Fastest1]

Looks like parts porn to me! I like it.

[Connor]

Looks nice. I wonder how well it'll do compared to a solid one.

[Hypnotoad]

Looks nice. I wonder how well it'll do compared to a solid one.

That's definitely the question. It's certainly no where as rigid as a solid block.

Was this actually that much cheaper than a solid block? A solid block would be what, $30?

[MikeSherman]

Well, for giggles I ran an FEA....

I placed 300lbs acting down about 5" off the face of my spacer and see about .0003" max deflection locally at the top while most of the mounting surface is at almost nothing. The spindle casting will also add rigidity which isn't modeled in my quick analysis.



If anything the effects of the column, dovetail ways and running clearance will be more of a factor than my spacer.

Mike

[Hypnotoad]

I placed 300lbs acting down about 5" off the face of my spacer and

Was this to model just the weight of the head? I was more concerned with vibration from the cutting action. There's a lot of force at work when you're cutting something.

[MikeSherman]

I don't know how much the head Assy weighs - let's say about 80lbs.

300lbs is just a number I chose to include cutting forces and dynamic loading.

It was just a quick 10min sanity check at work. +\- 100lbs won't make much of a difference in the results.

Id be happy to run a higher load Monday as its beer thirty and work for the week is done!

Your mileage may vary.

Mike

[DonKes]

An FEA is only as good as its model.

Often different analysis take different models.

Don

[MikeSherman]

Haha very true - tough crowd. ;-)

I often run different combinations of loading and restraints to check the sensitivity of my models. This part isn't going to the moon nor is it spacing the head on a 6-axis HAAS so I'm pretty satisfied with my quick and dirty sanity check FEA.

Maybe next week if I find some time I'll calculate actual cutting forces that could be achieved with this little mill and apply them to my model for the purists out there.

Mike

[MikeSherman]

The local cost for a block of solid 6061 2-1/2" x 5" x 8" is $55.

In my fabricated design I have about $46 worth of material.

I contemplated going billet - but liked the freedom of machinability of the fabricated design. If something didn't fit right or I screwed up along the way, I could easily replace the bad part.

-Mike

[MikeSherman]

Well I've received a lot of favorable feedback via PM's. Thank you all.

Looks like I have a busy weekend ahead machining a couple of these spacers for you fellas.

If you want one too - PM me for pricing details.

Thanks.

Mike

[CS900]

Sure looks perdy!

How's the parallelism between the front and rear faces?

[MikeSherman]

Parallelism should be pretty good. I face both sides after assembly. No reason for it to come apart after that.

I had the head shimmed on the stock mill, so I was prepared to shim with the spacer added if need be.

-Mike

[MikeSherman]

...busy couple of weekends. I finished a 2.5" and 3.5" spindle head spacer for a couple fellas on the forum. They turned out nice. Here are a couple pics....




-Mike

[pippin88]

Nice parts. Do you mind sharing some photos of the fixturing / work holding? In particular, do you cut each plate / part in one setup, including the outside / perimeter? Or do you size the part then do the other features?

[MikeSherman]

Pippen88 - I size my stock first and hold the parts in parallels in the vice. Most parts are 2 setups; top and bottom or top and side. I only have this one fuzzy pic I took...



-Mike

[MikeSherman]

I checked parallelism at work on a granite inspection table and I'm within .002" across the entire face. I say pretty dang good for coming off a G0704....which also has the spindle spacer installed.

I recommend checking spindle squareness after installation and shim as required.

-Mike

[mikegiraud]

I really liked the light weight head spacer design that Mike Sherman made, so I asked him to make me one, along with the column spacer. My G0704 has the factory installed DRO, which has the X-axis glass linear scale between the table and the column, which eats an inch of Y-travel. Therefore, rather than the typical 2" and 2.5" thick column and head spacers, I needed a 3" and 3.5" to get the same 9" that everyone else gets. Mike Sherman's machining was excellent. The spacers are beautiful, and installed easily. I used 170mm long M12x1.75 SHCS for the column spacer, and 6" long 3/8" T-bolts for the head, both from Ebay.

I had my base, column, and z-slide machined at a local machine shop to increase the Y and Z travels. I had the Z slide modified to "clone" the nut pocket 5.5" lower than the stock position (added thanks to Mike Sherman for this idea). Theoretically, this give me 5.5" more z travel without "flipping" the z-slide , but my Nema 34 motor mount limits it to an added 3" of z-travel which is plenty for now. The local machine shop charged me $225 with a 3 week lead time for the mods to my castings, as I caught them during a really busy month.

I'll be installing a Leeson 192067.30 metric D80 motor and Tormach 3-stage air cylinder based PDB in the next 2 weeks (waiting for the GS3-22P0 VFD from Automation Direct, which is back-ordered till May 12th) so the light weight head spacer was important, as I'll be adding quite a few pounds to the head. With Mike Sherman's spacers, I'm now enjoying 9" of y-travel even with the DRO glass scale in place. The 9" of y-travel opens up so much more utility for the G0704. For those like me, who where sitting on the fence pondering the increased Y-travel project, I highly recommend taking the plunge.

[hoss2006]

The 9" of y-travel opens up so much more utility for the G0704. For those like me, who where sitting on the fence pondering the increased Y-travel project, I highly recommend taking the plunge.

I agree, that's why I came up with the idea 5 years ago.
Hoss

[MikeSherman]

Mike - your mill looks great....time to get it dirty!!

Thanks for the positive feedback too - I'm glad everything worked out for you!

-Mike