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Author Topic: Myford Super 7 - adding ball screws  (Read 13812 times)

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Offline Hood

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Re: Myford Super 7 - adding ball screws
« Reply #10 on: September 09, 2012, 11:27:16 AM »
You can see them here except I dont have the end fixed in the housing I made for the thrust bearing so you dont see them extending again on the tailstock side.
http://www.youtube.com/watch?v=Kjtg5FATmAU

Hood

Offline BR549

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Re: Myford Super 7 - adding ball screws
« Reply #11 on: September 11, 2012, 10:34:44 AM »
Have yall thought about fixing the screw rigid and making the nut to spin? Would give you plenty of room under the Y axis plate and put the nut out the back side.

Just a thought, (;-) TP

Offline Hood

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Re: Myford Super 7 - adding ball screws
« Reply #12 on: September 11, 2012, 03:21:31 PM »
Presume you mean X Terry?
I thought about doing something like that as the advantage would be the motor would be fixed to the saddle but the downside was it would need a belt and pulley and a bit harder to get the bearings fitted on the nut.

Hood

Offline RICH

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Re: Myford Super 7 - adding ball screws
« Reply #13 on: September 12, 2012, 05:19:54 PM »
I did what Terry suggested. You may want to have a look at my Atlas conversion as I cover most of the steps.
http://www.machsupport.com/forum/index.php/topic,12484.msg80823.html#msg80823
I anchored both ends of the screw and one anchored end allows for adjusting preload of the Z. Did the same for the X axis.
Look at the pics carefully and you will see how the Z screw was adjusted from intial installation to final.

To proteact the screw i just mounted some Al angles which telescope to protect the screw. It works great.

It took a little bit more effort to make the screws adjustable but it paid off in the end. BTW, I use a torque gage to test/adjust and know just how much torque each component is using.

Have fun....
RICH

Offline Hood

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Re: Myford Super 7 - adding ball screws
« Reply #14 on: September 13, 2012, 03:05:13 AM »
Rich, maybe I am misunderstanding what Terry said or maybe misunderstanding the pics of your lathe but looks to me like you are spinning the screw rather than the nut.
Hood

Offline RICH

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Re: Myford Super 7 - adding ball screws
« Reply #15 on: September 13, 2012, 06:16:46 AM »
Hood,
Sorry, yes my screw is turning. Hmm..Eyes reading and engaged but brain not functioning yet.
To early in the morning. :D

RICH

Offline Hood

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Re: Myford Super 7 - adding ball screws
« Reply #16 on: September 13, 2012, 07:08:16 AM »
No probs Rich, thought I was going daft (or actually more daft if thats possible ;D )

Hood
Re: Myford Super 7 - adding ball screws
« Reply #17 on: September 13, 2012, 11:58:44 AM »
I was checking out some options where the ball nut spins and the screw is fixed ridgid(does not turn). Seems like other a hand full of companies there's not much out there for the DIYer. Maufacturers site lowered moment of inertia and space constriants as a few of the advantages, especially on applications with really long screws.

Robert

Offline Hood

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Re: Myford Super 7 - adding ball screws
« Reply #18 on: September 13, 2012, 02:52:41 PM »
Bridgeport did it that way on the X axis of the series 1 rigid rams, makes changing the belt a bit more awkward than it is on the Beaver mill.
Hood
Re: Myford Super 7 - adding ball screws
« Reply #19 on: December 22, 2012, 11:27:10 AM »
Well, I finally finished replacing my X-axis screw with a ballscrew.  I actually used one that I bought and had machined by John Stevenson to fit an X1 mill conversion I was doing, but them I bagged a Novamill on fleabay so the X1 got unconverted and sold!  The screw is a 5 mm pitch SKF, bought from Arc.  The main trick was to remove the nut (usual precautions) and re-fit the other way round so the cylindrical spigot points away from the lathe saddle.  (The problem here is that the original Super 7 L/S nut has a spigot 23 mm diameter that fits a bore in the saddle; with a flange to clamp on the saddle face.  The SKF nuts have a 24mm spigot.) Then I machined up a simple adapter plate which screws to the face using the original 4 BA bolts, and has 4 M4 tapped holes for the the ballnut.  A simple job on the CNC mill.  After fitting this everything went back together easily and the performance is much improved, it seems on an initial test to take off just what you tell it to, whereas with my previous plain screw it was very hit or miss.  If anyone is interested I'm happy to try to take some photos to show how I did it.  I will see how I get on with just converting the X slide, as fitting a ballscrew instead of the main leadscrew looks much harder.

John.