# CX605 Down Feed Tune Up



## YYCHM (Feb 23, 2019)

Finally got fed up with the sloppy down feed and head drop issues on my CX605 and decided to do something about it.






Apparently the head drop issue has to do with the poor mesh between the column rack and up/down feed gear as well as the sprung head support system.

I tackled the mesh issue by shimming the rack out 0.02".  I tried 0.013 first and that was fine, then I tried 0.026 and that was too much, so I settled on 0.02.  There is still a wee bit of backlash between the gear and rack still.  I may attempt to shim some more ...…  will see.

I'll look at replacing the head support system if the head drop issue persists.

Note the key way in the shaft.  The key for that is a major contributor to the down feel slop.






The slack in the mesh between the helical gear and handle seat is a big contributor to the fine fee slop.  To resolve this I decided to try powder coating the teeth.  It worked well and remove all of the slack when engaged.  Only time will tell as to how long it lasts.  I also powder coated the key for the rack gear shaft (see key way in first image). There was a lot of slop there.  3 PC applications made it fit nice and snug.






If you're interested in trying powder coating, this is my setup.  Pretty simple eh.  10min at 375F.






Now I need to shim the slop out of this dumb a.. arrangement.  Why this joint was necessary in the first place is beyond me.

Further updates as I piece it back together and test it out.

Later.


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## Bofobo (Feb 23, 2019)

YYCHobbyMachinist said:


> Finally got fed up with the sloppy down feed and head drop issues on my CX605 and decided to do something about it.
> 
> View attachment 4470
> 
> ...


My thoughts on the fine feed shaft is much the same as yours, i shimmed the joints as a temporary fix but i plan on a straight shaft, it should work.


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## Janger (Feb 23, 2019)

Nice upgrade.


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## Bfb123 (Feb 24, 2019)

I put the little “air shock” mode on mine that I ordered from little machine shop and it head drop problem resolved..... of course still a limit to depth of cut but much better


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## YYCHM (Feb 24, 2019)

I shimmed the joints in that articulated hand wheel down feed shaft.  I can't believe how much slop that eliminated between the helical gear and the hand wheel.  She's tight now.






I'll wrap the union (name per parts list?) with electrical tape for good measure.

Powder coating the adjustable union (piece in the middle) would have been another option.


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## PeterT (Feb 24, 2019)

That is a curious application for a universal joint. You would think there is enough latitude in the bolt up assembly to accommodate any misalignment that a straight shaft would work? Interesting.


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## YYCHM (Feb 24, 2019)

PeterT said:


> That is a curious application for a universal joint. You would think there is enough latitude in the bolt up assembly to accommodate any misalignment that a straight shaft would work? Interesting.



No kidding!  A internet blurb warns not to replace it with a solid shaft to.  Makes me wonder if it's a work around for faulty dimensioning of the wheel support block and the down feed gear support block?


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## Bofobo (Feb 24, 2019)

Bfb123 said:


> I put the little “air shock” mode on mine that I ordered from little machine shop and it head drop problem resolved..... of course still a limit to depth of cut but much better





YYCHobbyMachinist said:


> No kidding!  A internet blurb warns not to replace it with a solid shaft to.  Makes me wonder if it's a work around for faulty dimensioning of the wheel support block and the down feed gear support block?


so ... possibly some slots for the  dial mount could allign that? Where was that blurb?


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## YYCHM (Feb 24, 2019)

Bofobo said:


> so ... possibly some slots for the  dial mount could allign that? Where was that blurb?



That blurb is here..

http://www.machinistblog.com/the-mini-mill-head-drop-problem/

It may simply be one of those "don't believe everything you read on the internet" situations.  Dunno.

More on z-axis backlash here.

http://www.machinistblog.com/an-easy-way-to-reduce-the-mini-mills-z-axis-backlash/

Another thing suggested is to slot the screw holes on the fine feed worm gear mounting block as a means of improving the mesh between the fine feed worm gear and the down feed shaft.

I don't think I'll attempt that mod, I'm pretty happy with the improvement gained so far.


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## Brian H (Mar 10, 2019)

YYCHobbyMachinist said:


> I shimmed the joints in that articulated hand wheel down feed shaft.  I can't believe how much slop that eliminated between the helical gear and the hand wheel.  She's tight now.
> 
> View attachment 4481
> 
> ...



What did you use to shim that joint? I can't tell in the pictures. I was going to make a straight rod, but, now I'm going to look at the links you put up. I'm also curious as to why that joint is there.


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## YYCHM (Mar 10, 2019)

Brian H said:


> What did you use to shim that joint? I can't tell in the pictures. I was going to make a straight rod, but, now I'm going to look at the links you put up. I'm also curious as to why that joint is there.



I just used some .008 aluminum sheet stock I had.  Cut little U shaped pieces out and jammed them in the hinge points to take up the slack.


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## Brian H (Mar 10, 2019)

Here are a couple pictures of the setup I made


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## Bofobo (Mar 11, 2019)

Brian H said:


> Here are a couple pictures of the setup I made
> View attachment 4687View attachment 4688View attachment 4689


I like how this mounts, did you loose any travel? This same space is where i mounted my dro scale so the concept will not work for me but it is much more low profile than the MLMS.com version (theirs sticks out the top) but theirs extends the overall head travel allowing for bigger material or heavier tooling. My rack was shimmed with the steel banding that my mill was shipped with, and if i remember correctly an additional piece of shim stock


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## YYCHM (Mar 11, 2019)

I'll have to look at doing this mod.  According to Brian H that spring strut is a $15 item at PA.   I can't find anything like that listed on the PA website?


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## Bofobo (Mar 11, 2019)

YYCHobbyMachinist said:


> I'll have to look at doing this mod.  According to Brian H that spring strut is a $15 item at PA.   I can't find anything like that listed on the PA website?


https://www.princessauto.com/en/search?Ntt=Universal+Lift+Supports


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## YYCHM (Mar 11, 2019)

Bofobo said:


> https://www.princessauto.com/en/search?Ntt=Universal+Lift+Supports




Thanks!


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## YYCHM (Mar 11, 2019)

Hmmm... the only PA strut that looks like it would work is 17 3/4" long and supports 47#.  The stroke is 3/4" too short and 47# is a little over kill.  The LMS version is 35#.


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## Brian H (Mar 13, 2019)

I looked and it doesn't have a number on it. I just walked through the section in the store and picked one I thought would work. I don't recall what the rating was on it


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## YYCHM (Jun 21, 2019)

Made a significant discovery today.

I thought this screw was there to simply hold the down travel pointer onto the head.






Upon closer inspection it occurred to me that it looked suspiciously like a gib adjustment screw, so I tightened it up and re-locked it.

Well...…. the whole down feed mechanism tightened up and shed a LOT of slop.  The analog down feed dial now indicates very close to my Z-Axis DRO. It was nonsense before.

It would appear that the screw has a lot to do with stabilizing the down feed pinion shaft (name?) and holding the pinion gear close to the column gear rack.

No where in the users manual is the purpose of this screw mentioned.


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## DPittman (Jun 22, 2019)

YYCHobbyMachinist said:


> Made a significant discovery today.
> 
> I thought this screw was there to simply hold the down travel pointer onto the head.
> 
> ...


Sounds par for a Craftex manual.


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## YYCHM (Jun 23, 2019)

Here is some one that replaced the universal joint with a solid shaft.

http://www.hteck.ca/lathe-mill/mill_v-feed/mill_v-feed.html


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## YYCHM (Jul 5, 2019)

In April I had a plastic spindle drive gear disintegrate.  Member Brian H bailed me out by sending me his spare (Thanks Brian).  Shortly after the gear failed I ordered two more gears (backups) from BB.   Come July BB still hadn't supplied my spare gears:-(     I gave up and ordered the LMS belt drive and air spring upgrade kit.

At $300 landed it's a pricy upgrade for a $900 mill.  Worth it?

Boy, I'm impressed.   The belt drive was well put together and installed without a problem. The mill runs a LOT smoother with less noise and the air spring really changes how the down feed behaves.  Spindle travel increased from 7" to 10".

The kit arrived within a week.  Installation took maybe 4 hours at most (I picked at it after work drilling and tapping one hole at a time in the evenings).






What has resurfaced is an excessive amount of backlash in the down feed.  Once taken up the analog dial does match my DRO, so that's good.   I didn't shim the new Z-axis rack when I installed as I didn't have any shim stock long enough to accommodate the longer rack (a future project).

If you have a mini-mill this upgrade is well worth it IMHO.

LMS includes a laminated RPM chart to mount under the RPM/OFF/ON switch.  It calibrated well with my $12 tachometer.


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## Bofobo (Jul 6, 2019)

YYCHobbyMachinist said:


> In April I had a plastic spindle drive gear disintegrate.  Member Brian H bailed me out by sending me his spare (Thanks Brian).  Shortly after the gear failed I ordered two more gears (backups) from BB.   Come July BB still hadn't supplied my spare gears:-(     I gave up and ordered the LMS belt drive and air spring upgrade kit.
> 
> At $300 landed it's a pricy upgrade for a $900 mill.  Worth it?
> 
> ...


I dont have long shims in mine only 3 1” pieces. I tried my new treadmill motor conversion today and made .03 cuts like it was nothing. But following your advise on the gib screw for headstock adjustment i found i am missing the nut, and i need to enlarge the relief hole in my dro mounting to replace it


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## Johnwa (Jul 6, 2019)

YYCHobbyMachinist said:


> In April I had a plastic spindle drive gear disintegrate.     I didn't shim the new Z-axis rack when I installed as I didn't have any shim stock long enough to accommodate the longer rack (a future project).
> 
> .



What size of shimstock do you need?
I have a couple of rolls 6”x100”.  I don’t recall the thickness.

Cheers
John


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## YYCHM (Jul 6, 2019)

Johnwa said:


> What size of shimstock do you need?
> I have a couple of rolls 6”x100”.  I don’t recall the thickness.
> 
> Cheers
> John



Thanks for the offer John,

I need 0.02" X 3/4" X 13.5" or there abouts.  0.02" worked well with the original rack, the new rack may need something different.  I need to play around with it first.


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## YYCHM (Jul 6, 2019)

Bofobo said:


> I dont have long shims in mine only 3 1” pieces.



How in the world did you get three pieces of shim in there without taking the head off ????


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## Johnwa (Jul 7, 2019)

Craig
My shim stock is 0.001” and 0.002”.  Probably not the easiest way to get 0.02” but you’re welcome to a section if you want.

John


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## Bofobo (Jul 7, 2019)

YYCHobbyMachinist said:


> How in the world did you get three pieces of shim in there without taking the head off ????


tediously is the short answer, used the rack screws as shim stop pins and dropped them from the top, wedging to get them to drop, moving the head as needed to access screws.


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## eric_brackenbury (Jul 27, 2022)

YYCHM said:


> That blurb is here..
> 
> http://www.machinistblog.com/the-mini-mill-head-drop-problem/
> 
> ...


Good info thanks for the links, I have a metal rolling mill so can roll copper sheet and try that.


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