# ExCello power knee info



## Vector Warbirds (Sep 25, 2022)

Greetings!  I have an ExCello 602 mill and I am thinking about installing a power knee servo.  From what I have seen these mills need a more powerful unit than the run of the mill and hand cranking the ExCello compared to a Bridge you can tell the knee is harder to lift. Servo Company makes the 200 series but its over $1000 so no dice there.  Does anyone here have an ExCello with a power knee and if so I would appreciate your input.  I am pondering the use of a gear motor and making my own.  Have been looking at E bike motors of DC 24v 250w and chain driving to the knee shaft.  Ca Lem did a convert on his Bridge and looks like it works.  Just kicking around ideas at this point so your thoughts are appreciated.  Have watched all the Tube videos and not impressed with the cheap drives.

Cheers!


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## Hruul (Sep 26, 2022)

Welcome to the forum.  I cannot help you, but hopefully some here can.


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## PeterT (Sep 26, 2022)

Welcome. John installed an Align/clone? power feed on his BP mill as well as his prior mill. I can't say how comparable that would be to your Excello. There might be some other posts but this one rings a bell. There are also some Youtube vids (Clough42 maybe?). There's a few things to be aware of going into the project.









						New 10" X 54" mill ordered.
					

Could it be that the base is taller than on other BP clones? The height above the floor pads / foot mounting looks substantially beefier than even on my real BP.




					canadianhobbymetalworkers.com


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## LenVW (Sep 26, 2022)

I used a Ex-Cell-O #602 knee mill for years in the 1990s.
Last year,  I met a fellow who has done dozen of rebuilds of these mills.
His business focuses on the #602 mills.
He may have some direction for you.

PRESTON REBUILT MACHINERY
Roy Weidinger - Cambridge, Ontario
P. 519-621-4258


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## Darren (Sep 26, 2022)

I have an Align unit on my bridgeport clone.  It's also a 10x54 and has no problem at all lifting the knee with a 150#  rotary table,  60# vice,  and more. Should be easy enough to adapt.  I had to adapt mine too.


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## jcdammeyer (Sep 26, 2022)

I'm using a 750W Bergerda AC Servo.  I started with a 1200 oz-in stepper and it was way too slow for me and at higher speeds stalled.  Then when the Gecko DC Stepper drive failed I tried a crappy Leadshine stepper driver off Ebay that had a horrible whine.  So I went with the servo.  Haven't looked back.






And I've run this with a lot of weight without issues and now have proper metal pulleys and AC servos instead of the DC servos on X and Y.


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## jcdammeyer (Sep 26, 2022)

A friend of mine with a the next size up of our mill (his has horizontal spindle and larger X sized table) but we both have the heavy pivoting X axis mechanism.  Anyway, I believe he used a wheel chair DC motor at 24VDC.  He's not done CNC on this mill so it's just a power feed to make cranking it up/down easier.


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## Degen (Sep 26, 2022)

Put a digital torque wrench on it and measure the effort required to turn the crank.  If that's not available, use a wrench and fish scale and calculate the torque.  Once you have this this is the absolute min and is not recomended, I would use at least 1.5 that number if not 2.

Now you can determine the motor (stepper/servo or dedicated system you need).  Most of the motor systems are between 120-200inch/oz which is only (0.625-1.04ft/lb)  With servos (and stepper begrudgingly) you can easily direct drive without reduction.


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## jcdammeyer (Sep 26, 2022)

Degen said:


> Put a digital torque wrench on it and measure the effort required to turn the crank.  If that's not available, use a wrench and fish scale and calculate the torque.  Once you have this this is the absolute min and is not recomended, I would use at least 1.5 that number if not 2.
> 
> Now you can determine the motor (stepper/servo or dedicated system you need).  Most of the motor systems are between 120-200inch/oz which is only (0.625-1.04ft/lb)  With servos (and stepper begrudgingly) you can easily direct drive without reduction.


I did the same thing to determine the torque requirements for the lathe and the mill knee.
For the mill I started with Size 34, 600 oz-in running on about 50VDC and 3:1 belt drive.  I found that although it was useful for slowly up and down and easier than winding by hand it had very little speed.

I changed up to a 1200 oz-in with the 3:1 ratio.  Now I had better speed and still enough torque based on the motor curve drop off at speeds above 250 RPM.  

If you think about it, a stepper motor that pulls 6A per winding at 50V is 300W x 2 but in reality by the time you get a decent velocity the current is far less.  Assuming you did get at least 3NM at speed that's just over 2 ft.lb.  

I may well have been off base using 3:1 for torque increase at the cost of lower torque at higher RPM.  Might have been on the wrong side of the curve and direct drive would be better.

Now with the 750W servo and 3:1 I get decent speed and still adequate torque.


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## Degen (Sep 26, 2022)

This is the reason I used servos, 260in/oz with a peak of 1100in/oz.


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## jcdammeyer (Sep 26, 2022)

Degen said:


> This is the reason I used servos, 260in/oz with a peak of 1100in/oz.


Yes.  And they are so quiet too.  I have 3:1 on my X and because the Y has to carry the extra weight I have 4:1 on it.  I'm finding 180ipm a bit scary actually.  So easy to run into things. 
Mine are 180 oz-in peak 538 oz-in and on X that means 540 oz-in and 1614 oz-in peak.


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## Degen (Sep 27, 2022)

Mine are direct feed, no reduction and run peak of 100ipm, most machine is done at 20ipm won't go much beyond that as column stiffness and motor hp become an issue.






						ClearPath SDSK Models | Teknic, Inc.
					

ClearPath servo motor specifications for Step & Direction NEMA 23, 34, 56, & 143 SDSK models. Compare Torque-Speed curves, solid models, and power ratings.




					teknic.com


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## Degen (Sep 27, 2022)

@jcdammeyer how are you getting 180ipm with your setup?

I assume you are using 0.1"/rev for your screws, you max allowing for reduction at 1000rpm (3:1) is about 100ipm at 750rpm (4:1) drops to 75ipm.

I have yet to change out my ACME screws to ball screws and depending on the pitch will change my top ipm. It is on the list as driving the machine the way I do the screw nuts won't last.


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## Vector Warbirds (Sep 27, 2022)

LenVW said:


> I used a Ex-Cell-O #602 knee mill for years in the 1990s.
> Last year,  I met a fellow who has done dozen of rebuilds of these mills.
> His business focuses on the #602 mills.
> He may have some direction for you.
> ...


*Thanks much, trying to make contact.  Might be best for me to just buy a crane scale and have an exact number, then I can use the scale to weight pipe dream fish  Cheers!*


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## jcdammeyer (Sep 27, 2022)

Degen said:


> @jcdammeyer how are you getting 180ipm with your setup?
> 
> I assume you are using 0.1"/rev for your screws, you max allowing for reduction at 1000rpm (3:1) is about 100ipm at 750rpm (4:1) drops to 75ipm.
> 
> I have yet to change out my ACME screws to ball screws and depending on the pitch will change my top ipm. It is on the list as driving the machine the way I do the screw nuts won't last.


I'm also still with ACME and the knee is 0.25" per rev (4 TPI).  X and Y are 5 TPI (0.2" per rev).   The knee moves up at a max of 120 ipm, Y at 150 ipm and X at 180 ipm.  So when I tell it to do a tool change it goes really quickly to the tool change position.  I'm likely wearing out my ACMe screws.


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## David_R8 (Sep 27, 2022)

jcdammeyer said:


> I'm also still with ACME and the knee is 0.25" per rev (4 TPI).  X and Y are 5 TPI (0.2" per rev).   The knee moves up at a max of 120 ipm, Y at 150 ipm and X at 180 ipm.  So when I tell it to do a tool change it goes really quickly to the tool change position.  I'm likely wearing out my ACMe screws.


Hehehehe I have the rapids on my router set to 9000mm/min or about 350 IPM


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## jcdammeyer (Sep 27, 2022)

David_R8 said:


> Hehehehe I have the rapids on my router set to 9000mm/min or about 350 IPM


Yes but your router is like a mercedes compared to my milling machine Datsun 510.


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## David_R8 (Sep 27, 2022)

Well this is a Datsun 520 
<hijackoff/>


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## Doggggboy (Sep 27, 2022)

David_R8 said:


> Well this is a Datsun 520
> <hijackoff/>
> View attachment 26808


Yours?


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## David_R8 (Sep 27, 2022)

Doggggboy said:


> Yours?


Oh gosh no, that is the BMW-killer Datsun 510 raced by Brock Racing Enterprises way back in 1971/72.
When I was a kid I had an AFX racetrack set and one of the cars was a BRE 510. For some reason I love the let's-get-down-to-business attitude of the 510.








						1-On-1 With The BRE Datsun 510 And The Man That Drove It To Trans Am Victory
					

John Morton’s unlikely success is perhaps as unlikely as one of the cars that he drove




					petrolicious.com


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## jcdammeyer (Sep 27, 2022)

David_R8 said:


> Well this is a Datsun 520
> <hijackoff/>
> View attachment 26808


Nope.  Still a Datsun510.  Just further along on the paint job from what mine looked like:




And probably faster than mine too.


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## YYCHM (Sep 27, 2022)

jcdammeyer said:


> Nope.  Still a Datsun510.  Just further along on the paint job from what mine looked like:
> View attachment 26812
> And probably faster than mine too.



Where was this picture taken?


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## jcdammeyer (Sep 27, 2022)

YYCHM said:


> Where was this picture taken?


Edmonton.  Griesbach military base I believe.  Back in about 1975?  The 510 had shorter/stiffer springs with the pivot arms slotted to fix the camber issue.  Stiffer sway bar in the front and a new sway bar for the rear. A 2" exhaust system with Corvair muffler and nothing done on the engine.  The fibreglass fender parts came from California from I think the same place that did Paul Newman's Datsun.  We belonged to both the Edmonton Light Car Club (rally driving) and I forget the name of the Autoslalom club.  We'd also go down to Calgary for Slaloms at that old airport runway on the north end.

And as usual I've hijacked yet another thread.  Sorry.


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## jcdammeyer (Sep 27, 2022)

Boy, haven't looked at this book in decades since the car was sold a long time ago.


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## Degen (Sep 27, 2022)

David_R8 said:


> Hehehehe I have the rapids on my router set to 9000mm/min or about 350 IPM


Ha Ha I have a friend that's pushing 600lbs at 600IPM  and a potential supplier that has a machine doing 1000IPM who machine AR500.

The sad part is these machine are in excess of a million dollars.

Forgot to mention the owner of the 600IPM machine is always looking for the loads to break off when it kicks it to full speed.


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## Rauce (Sep 28, 2022)

LenVW said:


> I used a Ex-Cell-O #602 knee mill for years in the 1990s.
> Last year,  I met a fellow who has done dozen of rebuilds of these mills.
> His business focuses on the #602 mills.
> He may have some direction for you.
> ...



I tried contacting them about my rebuild project some months ago with no luck, email and phone… 

This was about my lathe though. I also have a 602 that could use some work that I’m not equipped to do… I wonder how much they would charge.


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## LenVW (Sep 29, 2022)

Roy is pretty busy.
His main work is with Ex-Cell-O #602 vertical knee mills.
Try his ‘cell’ . . . 519-240-4676


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