[Bird_E]

Has anyone tried to use Linear Rails for the Z-axis of an RF-45 clone machine and eliminate the Dovetail?

I would think this would make a much smoother Z-axis? Has anyone tried it or have any thoughts about this? I did see one post where someone is mounting the rails on the sides of the column in a seudo Slide/Dovetail combination.

Thanks!
Bob

[SMW Precision]

Has anyone tried to use Linear Rails for the Z-axis of an RF-45 clone machine and eliminate the Dovetail?

I would think this would make a much smoother Z-axis? Has anyone tried it or have any thoughts about this? I did see one post where someone is mounting the rails on the sides of the column in a seudo Slide/Dovetail combination.

Thanks!
Bob

Bob, the IH System use a slide configuration if Gibs are correctly adjusted and lubricated there is little difference in resistance versus a ball bearing slide system. Several people have done this type of conversion with RF45 mills. I suggest you post the question in that forum and search through CNC zone posts for the topic.

[kentavv]

You might check in the following thread...

http://www.cnczone.com/forums/showthread.php?t=35961

[Cruiser]

Bob
I'm the one that added slides rails to my "Z" axis. Reason was briefly that to draw my gear box up with the gib to pull the box slideway to the column slideway ended up with too tight of gib and binding. loosening gib allowed box to droop from slideway and we refer to this as cantelevering. I didn't get along with the gap at the top of the slideway so started figuring this system and it works good ! Now i have gib @ zero to control any possible rotational forces of gear box and the rails to pull the slideways together. All in all i feel that the sliding resistance is less by far than it was trying to adj it with gibs alone and keep in mind mine is the 10" square v3 model and the new 12" is supposed to be much stronger. your mill should be capable of carying rails like mine but the process of milling the colomn with a router on a bracket clamped to sadle got a bit hairy and not too pretty, but its functionality that is needed ! Figure on keeping the doves in use if you add rails and good luck !

[Bird_E]

I did see you posts on adding the slides to the sides of the column.

1. Do you even need the gib and dove tail now that you have the slides on the machine, and if so why?

2. do you think it would be possible to mill off the dovetails and mount the slides to the front of the column?

Thanks!
Bob

[Cruiser]

BOB,
Yes the gibs are needed, as the rails can't support the forces generated in all directions. The two together tho work to such a degree that I won't change it now, I like it !
You could mill off the doves and then re engeneer the slides, but rails such as mine may not be strong enough in the bearings after the mounting is disigned for carrying the heavy gear box. As stated above, the two work together and have solved the problems i had admirably. Cantelevering is abolutely NO MORE ! and i don't have a shaking gear box or trouble tramming in "Z" any more. the whole machine feels much more stable and no more sticksion since gibs are not near as tight as they once were.

[deon]

Hi

I am in the process of installing rails to my Rf-45. The X and Y axis are done. Haven't gotten to the Z yet. Still busy mounting the ball-screws.

I do agree by setting the gibs you might come close to smooth movement and fair accuracy, but in the long run slides is almost everlasting on a hobby mill as the RF-45. That much cant be said of the quality of the castings of the RF-45 mills.

This is why I am taking the time and effort to strip down my brand new never used RF-45 mill to install linear slides and ball screws.

Cruiser has got me worried now about the rails on the Z not being capable of handling the forces. I will have to check this out very carefully.

Thanks
Deon

[Bird_E]

Deon,
Can you post some pictures of your rails for X and Y or give a little more info!
THAT WOUDL BE GREAT TO SEE!

Thanks!
Bob

[deon]

Hi Bob

OK. It's sleeping time in South Africa now.
I will take a few pics tomorrow and post it same time tomorrow.What I can say for now is, I used THK SR15 linear slides.
Had to cut some of the dove tails away but it looks good and works great.
I must say it is really heart breaking to cut up a brand new machine but I think in the end it will be worth it.

Talk to you again tomorrow.
Deon

[deon]

Hi Bob

Hope you can make sense of the pics. Any questions let me know.

Just for interest sake , The pic of the complete assembly you can see my sons hand.......It must have been standing at a slight angle he had to steady it other wise without the ball-screws attached it runs away by it self.

Movement is as light as a feather and very precise. All rails have been mounted on the original slide surfaces only pockets was cut to take the bearing blocks and part of the dove tails has been removed.

Thanks
Deon

[Bird_E]

That looks pretty sweet!

Couple of questions:

What size rails are you using: 25mm, 15mm etc....

What kind of machine did you use to do all the machining work on the RF45?

Do you need to leave the overhang on the rails or will they be trimmed?


last questions, do you loose any travel doing this conversion!


NICE WORK!!!!!
Bob

[Bird_E]

What did you use for datum surfaces so that everything remains square?

Thanks again.... I'm drooling!
Bob

[deon]

Hi Bob

Rails THK SR 15
Machining done on a Bridgeport.This is not necessary because as I said the only critical machining is on the cradle(Pockets for the bearing blocks)
The rails is mounted on the original machine slide surface(no machining except for the drilling of the screw holes)
The pieces of the dovetails that have been taken away is just for clearance of the bearing blocks. Its not machined all the way down to the slide surface.

No travel are lost. Actually you gain quite a bit. On the y axis you will see I stole about an inch and a halve by lengthening the slot in the pic.
I am moving my y axis servo to the back of the machine.
You can remove the overhanging rails if you want but I think I am going to leave it there for now.
I will measure the actual working envelope and tell you tomorrow.

Thanks
Deon

[deon]

Hi Bob

I missed your other question about the datums.

Befor I striped the machine I clocked up the movement in relation to the ground sides of the machine bed and the ground sides of the cradle.

Well as you guesed .......I then used that as datum for square ness:cheers:

Thanks
Deon

[Bird_E]

What have you decided to use for servo motors?

Thanks!
Bob

[Cruiser]

It looks pretty solid and doing the same thing to the "z" MAY be worth it, I'd still like to see how it holds up to the beatings it will receive before i cut off all that cast iron. Its definately a one way trip, just like my gear box was/is ! hope it all works out for you

[Bird_E]

Here are some pics of my X3 CNC mill doing some work on the rf45...
The setup was a little interesting! The 3/4" 5" end mill in that little machine is not working out too well! I going to have the guys at work with a big VMC finish it up for me!


Bob

[Cruiser]

Yep ! I ran into the same thing using a large cutter with my mill. I dropped back to a smaller diam and cranked up the speed with much better success.

[deon]

Hi Cruiser

I really hope that this will work. The rails I am using has got 4 rows of balls at different angles in each bearing block so I hope it will cope with the forces.

I am more worried about the cap-srews keeping every thing together(5mm)

For minimizing cutting forces I opted for more speed and lighter cuts.

But the biggest reason for going with linear rails and bearings was wear and accuracy.

Thanks
Deon

[deon]

Hi Bob

After seeing your pics I recognized your workshop and now I know who I am talking to.(Bob Berg) I am a frequent visitor on your site to see what you are up to. Nice work!!

Your base of the RF-45 looks much smaller than mine. Have you got a pic of the complete machine?

Anyway ,I have changed my working envelope from X530mm Y195mm to a much improved X650mm Y 260mm.

By keeping the overhanging rails I can go up to X725mm Y305mm.

The servos I will be using are Reliance Micro 100(E660) approx. 650 onces/inch.

Thanks
Deon