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Dick Payne
09-12-2002, 01:28 AM
I am a novice at home shop machining.I recently purchased a rf30 mill/drill that had very little use in a home shop. The spindle has about .030 backlash in the worm gear. Does anyone know of a back issue of HSM that shows how to correct this problem?

I started out with a Smithy 1220 3 in 1 machine but soon found out the mill isn't strong enough for what I wanted to do. I found a good deal on the mill/drill. Now I have to sell the 3 in 1 and am planning to buy a grizley 12x36 gear head lathe. I was warned about buying a 3 in 1 machine but am short of space. It is amazing how I found the space after using the 3 in 1 for a year.

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Dick

barts
09-12-2002, 02:15 AM
Hi Dick -

I've had a RF30 for 12 years or so; I'm also
quite limited on space... the usual way these
machines are configured is with a strong
spring that lifts the quill. This allows one
to use the drill-press style handle or by
engaging the worm feed one can use the
handwheel. Since the load is always up the
backlash in the worm isn't an issue. If the
quill is sticky, this won't work well for you. You might try cleaning and lubing the
quill to see if that helps.

Good luck -

- Bart


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Bart Smaalders
http://smaalders.net/barts

SGW
09-12-2002, 08:51 AM
You'll always have backlash, the best you can do. You need to learn techniques to allow for it, mainly, always take up the backlash in the same direction.

The problem comes with something like a quill downfeed, where the slop can cause the quill to drop down more than you intend and more than the dial reading indicates. I've found that one thing that helps is to engage the quill lock slightly, to provide some resistance while moving. When you're actually milling you ought to lock the quill anyway, of course.

There is probably no way to get rid of the backlash you have, short of replacing the worm and/or wormgear. You might be able to reduce it by moving the two closer together, but short of serious machining to plug the existing wormgear shaft holes and boring new holes, I doubt there is any way to do that, either.

Use backlash compensation techniques, same as you use for the table leadscrews.

howard w. evers
09-12-2002, 09:52 AM
<font face="Verdana, Arial" size="2">Originally posted by Dick Payne:
I am a novice at home shop machining.I recently purchased a rf30 mill/drill that had very little use in a home shop. The spindle has about .030 backlash in the worm gear. Does anyone know of a back issue of HSM that shows how to correct this problem?

I started out with a Smithy 1220 3 in 1 machine but soon found out the mill isn't strong enough for what I wanted to do. I found a good deal on the mill/drill. Now I have to sell the 3 in 1 and am planning to buy a grizley 12x36 gear head lathe. I was warned about buying a 3 in 1 machine but am short of space. It is amazing how I found the space after using the 3 in 1 for a year.
</font>

Dick:
I experienced the same problem with my RF-30. Solved it (easily) by installing a dial indicator and a target/stop on the head casting. Email me for details, if needed.

hwevers@charter.net

Herb Helbig
09-12-2002, 10:54 AM
My fairly new RF-30 has about 0.013" backlash in the fine down feed, but
the quill spring seems adequate to take it up. I quickly got irritated by having
to set the down feed dial with an Allen wrench, so replaced it with a 1/4-20
thumb screw. Had to grind the thumb handle down some, and also carve
some plastic out of the front cowling so it would clear.

Has anyone a good technique for keeping the head from rotating when raising
and lowering? It would be nice to have a good straight vertical surface to
indicate against.


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George Hodge
09-12-2002, 11:22 PM
Herb,our son gave me a cheap laser pointer,which I figured I needed like another ear. It laid in a drawer for about six months till I read something about using it to realign the mill head. Stuck it to the head with a magnet and spotted it on a vertical line on the other side of the shop,about 20 ft. I can raise and lower the head and still be almost dead on,when I use it.

Dick Payne
09-13-2002, 12:04 AM
http://bbs.homeshopmachinist.net//smile.gif WOW THAT WAS FAST!!!
Thanks to all of you for your input.

Howard-- Thanks for the photo's.
I bought a cheap DRO made in China for $49 on ebey. It appears to work well (within + or - .001 compared to my Mitutoya digital caliper) I will mount it in the area where you had the dial indicator.
Thanks again.
Best Regards:
Dick


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Dick

SGW
09-13-2002, 08:52 AM
George, that is one heck of a good idea!

docsteve66
09-13-2002, 10:15 PM
I have friend with the head moving problem. Asked for a solution over a year ago. I had none. You idea should solve his problem. Thanks.

Steve

Herb Helbig
09-13-2002, 11:06 PM
George! Laser is great idea! Thanks so much. I've been
thinking about using a laser + spring loaded mirror as a
test indicator for centering work in 4-jaw chuck, but my
rusty old brain never made the connection to the mill head
problem.


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Dick Payne
09-15-2002, 03:34 AM
Howard:
I mounted the $50 DRO by replacing the quil depth gauge assembly with an 11 inch peice of 3/8 all-thread. I locked the die cast slider nut from the depth gauge assembly between 2 lock nuts and re-installed the front plastic cover and depth gauge plate. I then tied the die cast slider nut to the slider bracket of the DRO. The top of the DRO I mounted to the pully housing bottom cover and the bottom mounting bracket of the DRO to the plastic front cover left hand gage plate mounting screw nole with stand offs. It appears to be stable enough and checked out to within 0.001" over 4" travel. In order to get the full 5+ inches of guil travel I would have to make 2 special brackets and lower the DRO by about 1".
I may do that later if I find I need the extra 1" of travel.
In your experience have you found you needed 5 inches of travel on the quil?
Regards:
Dick




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Dick

debequem
09-15-2002, 07:19 PM
5" of travel is not enough for me.

I would have bought one of those Blake centering tools if it would fit, but NOOOO. ;-)

Such is life with a mill/drill.