z axis alignment

Discussion about the CNC Shark Pro Plus HD

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Rando
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Joined: Tue Jan 06, 2015 3:24 pm
Location: Boise, ID
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Re: z axis alignment

Post by Rando »

It WORKED!

You might have read my post above where I mentioned getting a new spindle, 80mm diameter, needing to cut an aluminum mount plate, but having to use the existing router which isn't aligned in Z....

Well, over the last couple days I've been getting the spindle in it's more-permanent mounting form. On first install, the large tubes of liquid coolant were hanging from the ceiling, and I could tell the z-axis was moving as I took more or less of the weight off those tubes. Well, now I have a much better cooling-tube routing.

And, the results are in: it freakin' worked! I took the skewed aluminum plate, flipped it over, and mounted the spindle in that. put a readout indicator on a magnetic base, and measure out-of-position along the spindle body. Over about 5 inches in Z, the spindle body was less than 0.0025" (yup, 2.5 mils). That includes a 30-mil thick strip of skived PTFE (Teflon) tape under the lower two bolts that hold the plastic to the metal Z-mount plate.

So, I'm going to say that it's a huge improvement. Before, I could actually SEE the router bit wasn't perpendicular, and it was clear. Over a 1" thick piece of material, the top and bottom were out by 20-30 mills, depending on direction.

The absolute-Z of the bearing rails is still there, but hopefully diminished a tiny bit by me mounting the chip-blowing air, wires, and coolant spindle tubes and valves on backside of the gantry plate. The sag from that was previously around 2.5mils over about 12" in the Y (along the bed; very likely your X unless you swapped axes).

Thus, I will recommend it. Take your router just as you have it now, get some aluminum or HDPE, and using that router, cut out the new bracket. Make sure that the orientation of the new plate is "the same" on the bed as the plate being used to make the new one. Then, flip that sucka over and use it in place of a the stock mount.

(Yes, before you all start flaming, I do know that the two (front and rear) walls of the router opening won't be precisely parallel. But at least in my case, that doesn't seem to affect clamping effectiveness or positioning.)

Regards, and hope the update is useful.

Thom
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

jcatcmc
Posts: 18
Joined: Mon Jun 06, 2011 4:45 pm

Re: z axis alignment

Post by jcatcmc »

I don`t know if this approach has been tried but the over .5 mm (.023" ) sag in the middle of the X axis was starting to give me some grief.( see photos ) I decided to play around adding a counter weight to the rear of the Z axis motor. With a bit of experimenting if I mounted a 4.5 lb weight 350 mm ( 14" ) out from the center of the Z motor the overall deflection was reduced to .15mm (. 006 " ) This was checked out using a spindle mounted dial indicator on a straight edge. Thinking that adding extra weight to the travelling gantry was in its self going to create problems in deflection of the bearing bars I decided to let it go at that . Didn`t want press my luck too far.
Has this approach has been covered before ( I have searched the forum but no luck )?

1 photo shows unwanted tapering undercut on sides. ( Job is cupboard door fronts )
1 photo shows after counter weight added.
1 photo shows Fred Flintstones version of `proof of concept ` image

John
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Rando
Posts: 757
Joined: Tue Jan 06, 2015 3:24 pm
Location: Boise, ID
Contact:

Re: z axis alignment

Post by Rando »

See what they're makin' us do? Good you're not willing to put up with the silliness any longer.....

You could also do like I did and make one of these:

http://www.thomr.com/DropZone/MegaMouth ... pt2020.mp4

Rigidity and alignment solved :D
2020-012-030 Mega Mouth Update Installation and Alignment Guide v1.07.001.pdf
....the installation and alignment manual.
(3.55 MiB) Downloaded 210 times
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

jcatcmc
Posts: 18
Joined: Mon Jun 06, 2011 4:45 pm

Re: z axis alignment

Post by jcatcmc »

Just checked out that Mega Mouth video, Geez that thing looks like it was removed from the Terminators guts.

Rando
Posts: 757
Joined: Tue Jan 06, 2015 3:24 pm
Location: Boise, ID
Contact:

Re: z axis alignment

Post by Rando »

Check the manual....The trick to fixing the older sharks is that you need to beef up the gantry plate and the horizontal drive plate underneath the bed.
Only after that's been done will the gantry be stiff enough that the replacement carriages will be a benefit. A fun fact is the carriages are only 2 oz.
heavier than the original HDPE carriages. So, the weak motors and all that can stay the same.
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

jcatcmc
Posts: 18
Joined: Mon Jun 06, 2011 4:45 pm

Re: z axis alignment

Post by jcatcmc »

Hey Rando , If I was 40 years younger I`d be right into it , I`ve got all the gear , lathes, mills, ect. but at 73 you start and wonder how long your gonna last .I figured if I get to 112 I will clear my current work load.

jc

Rando
Posts: 757
Joined: Tue Jan 06, 2015 3:24 pm
Location: Boise, ID
Contact:

Re: z axis alignment

Post by Rando »

Most others just sent me the $900 + shipping and I made one FOR them ;)
There was the guy who only wanted to pay $300...but I didn't make one for him.
It takes ONLY 340+ toolpaths for the 10 parts.... :cry:

Cheers! Hope your mod gets you some great cuts. Any time that happens, it's a Good Day in Sharksville.

Rando
=====================================================
ThomR.com Creative tools and photographic art
A proud member of the Pacific Northwest CNC Club (now on Facebook)

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