THE GRIZZ

[Joey5226]

I'm sure I'm not the only one that checks back time to time for updates.

[atomarc]

I'm sure I'm not the only one that checks back time to time for updates.

Joey,

We're still here, haven't given up yet. We are diving into the electrics and electronics so there isn't lots of neat pictures to share. School has started for Nick and ordering and waiting for parts has slowed the progress...but we'll get back in the rhythm real soon. Thanks for the interest.

Stuart

[Fastest1]

I'm sure I'm not the only one that checks back time to time for updates.

You arent ;-)

[atomarc]

Well thanks for the interest..it keeps Nick and I going for sure.

Instead of sharing something we have done on the project, I would like to ask a question!! I'm having a real hard time with the spindle bearing setup. I have run it in per suggestions on this site. I've pulled it out, cleaned it, carefully 'Klubered' it, and with the utmost care, set the bearing preload, and although it does run cooler than before, I'm not sure we're in the ballpark yet.

The last go around was at 4600 RPM and the lower spindle bearing was right around 128 deg F. All this is with Nachi tapered roller bearings top and bottom, adjusted to zero endplay but no real preload on the assembly..just finger snug.

What is a realistic temp range I should expect? I have read about everything from 83 degrees to 140 degrees...not sure who's being honest. It really shouldn't be this difficult, maybe I'm overdoing the whole thing!

The best information I have found so far was posted here 5/17 by DJEkim33...a real analytical look at the bearings and their temps.

What do ya think gents?

[photomankc]

I would call that pretty good. If there is no play in the in the spindle and it's holding at 128 that's not too bad. My new TRBs ran at around 135 for a while but after a few months that came down to 115 to 120 at 5500 RPM.

My current machine is taking some time to run in. The upper spindle bearings (deep groove) were running around 145 to 150 at 4500RPM. I have had to make a few runs at it following SKF's break-in procedure which is to run them up to a cutoff point. I picked 145 and then stop and let them cool down and start again. I had to work my way up from 3800 RPM. I can feel they are now much less stiff than they were after install. Still need to break down the spindle cartridge and re-grease them but expect I'll have to follow a similar procedure with the spindle cartridge installed.

I'm now able to hold at 135 degrees at 5000 RPM speed so it's warmer than I would like but I think it will calm down after some run time. Less heat is better though for Z accuracy.

What I have read puts the red-line at around 180 degrees actual bearing temperature (housing + ~20 degrees).

[Chris D]

Hi Stuart,

I don't have much experience with Tapered roller bearings, however, I have always done about what you stated. I would run the nut to finger tight, lock the nut and run it.

That temp doesn't seem unrealistic. For precision spindles with angular contact bearings, ours ran cooler than that, but not much - maybe 20 degrees. As these were for very high precision grinders (work heads), we would also flow coolant over them to maintain a constant temperature. When building the spindles, we also NEVER would let the bearings (With Kulber) get over 200 degrees.

I suspect what you may want to do is just wait till you can cut with the machine. Milling with it will quickly tell you if you are too loose as it will chatter like crazy. Your assumption is correct regarding too tight - that will cause heating.

Just as another side note, over-packing bearings with too much grease can cause them to overheat too. I never understood how or why, but I know for certain the bearing mfg will specify exactly how many CCs of grease to use. For precision spindles like have built, it was certainly less than what I would normally do with car axle bearings.

Chris

[atomarc]

After removing excess grease from the TRB's ... reassembled & installed... easy drop of 20 degrees right off the bat... its crazy how such a seemingly small amount of "goober" can keep the rollie bits rolling. I feel more comfortable moving on with the rest of the build now that the temps seem reasonable. Going to proceed with doing the electronics side of things and "fine tune" mechanical gremlins that might pop up once everything is up and running. Stuck some of the head sheet metal on for the first time.... it was exciting!.... couldn't resist the temptation.....



Vroom vroom!

[atomarc]

[photomankc]

As long as there is no play in the spindle, sounds like you done good. Very small changes in preload can have a pretty major impact on running temp.

[atomarc]

As long as there is no play in the spindle, sounds like you done good. Very small changes in preload can have a pretty major impact on running temp.

The last attempt at spindle set-up was done on the bench with a DTI to measure any play in the bearings/spindle. Moderate wiggling produced the absolute slightest movement of the needle, maybe a tenth. Running it now at higher speeds, close to 5000 RPM only gets the temp up to 100 degrees or so. We call that good but the real proof will be when we run a part.

Stuart

[atomarc]

checking things off....





(the tail of all pigs)



(motor wired)

[atomarc]

[atomarc]

[atomarc]

Stickers came in a few days ago..... lets just say they got stuck! ....










"i present to you!" lol . What machine could be complete with out a name?! ... My cousin did a killer job on the art / font work! thanks cuzzz $$$




Keyboard and monitor got the velcro treatment..









Pretty slick how the usb cable tucks nicely!! =)




Question for the CNC electronics guys! All the momentary switches that will be connected to inputs (not estop) .... is it ok to tie / wire all the grounds together or does each input need its separate ground at the input buss? This is using a ESS from CNC4PC...or do these inputs get pulled high with the on-board 5volts. Not at all clear on this.

[atomarc]

(Y stepper motor installed....)





(Also cycled the table to its extents to size up the stepper wire length)

[atomarc]

progress on the electronics enclosure..... managed to get more duct in than anticipated.... but its still going to be... "snug"








(all the crap from the enclosure has now be run, bundled, taped,zip-tied,glued,screwed... and zip-tied in its final location awaiting the "box" for final makeup, also did a test fit of the enclosure / cable glands / associated wires. Things are getting busy in this general area! haha ... seem to be a theme lately









As the zip-ties clip I here the words of my brother in the back of my head... "dude always double the size you think you need"....


Nuc power button.... USB hole for your "stick" and dizzconnect.





Coming along....

[atomarc]

WHAT.....no comments on the selected name " Alpha MILL". I thought it was sort of cool as it's our 'alpha' version of the mill. I'm hoping in the tech world that 'alpha' means the first iteration.

If that name is trademarked somewhere else I guess we'll have to rip the sticker off and start fresh.

Stuart

[Kenny Duval]

We all know the stickers will get pulled off later once you use it and decide what you want to change.

That's turning out to be very nice though.

[atomarc]

Kenny,

When the last screw is screwed and the last wire is wired, I'm going to retire to my easy chair with some good books and a crossword puzzle. Any future changes on that thing will be Nick's bailiwick..and his dough too. It's been fun but I'm ready to be done and move on, although learning how to make stuff with it may pique my interest.

Thanks for the kind words.

Stuart

[Chris D]

Hi Stuart,

The machine is coming along fantastic. The fit and finish, the details, everything is just fantastic. You and Nick are certainly on par with some big-time machine tool builders - be proud of what you guys have accomplished!

As for "Alpha Mill" - my interpretation of it was "Alpha" as in Alpha male, the dominate one. I get your concept too about it being your first, mine just has a stronger bite ;-)

Chris