Any ideas on how to fit a 32mm ballscrew into a benchtop X-axis?

[kalbin]

I couldn't pass up buying this 32mm x 60 inch ballscrew but it won't fit my Industrial Hobbies mill. I knew it wouldn't but still haven't given up totally on figuring a way to make it work. The OD of the main section of the ballnut is ~2.45" which is much too big to fit under the X table. I think there's just over 1.25" between the X table and Y carriage, but don't quote me on that.

I think a 20mm screw would be ideal but I haven't lucked into a long enough one yet. I want one >44" and am hoping to avoid a rolled one.

So, has anyone come up with a clever way to externally mount a ballscrew on a benchtop converson?

TIA,
Ken

[rustamd]

what motor are you planing to use for driving the 32mm ballscrew?

[kalbin]

I.ve got steppers with a 2:1 timing pulley setup. They're around 850 oz-in as I recall.
There's also a lot of drag within this ball screw from the plastic wipers so I'm planning to replace them with something else. Otherwise, it'll be great once I reassemble it.
Ken

[cjmerlincnc]

Hi, I know what it feels like to pass up a good deal but really! Although I can talk, I recently bought a cheap trailer that looked good in the pic on Ebay but when I got there it was huge. My poor car struggled to get it home and a week later it was up on Ebay again.

Have a look at the Hafco mill in the forum, Good pics and he's designed the end extended with the ball nut partially out to the side of the axis.

Hope this helps.

[davo727]

Hi, Now find a killer deal on a set of 25 or 35mm linear rails and bearing blocks and mount the bearings to some precision custom spacer blocks on top of the X, Y saddle and mount the rails to the bottom of the X table. Make sure the bearing assys are rated to work inverted. That will jack the table up a couple inches and give you room for the big ultra ballscrew!

[davo727]

Actually the 35mm would be way too big. 20mm or 25mm would probably be fine.

[kalbin]

Interesting idea davo, but really tooo much work-around for me for a ball screw. I'm inexperienced and have little enough time to play in my shop, so will sooner break down and buy a rolled ball screw that will fit. The 32mm screw will fit into a project eventually.

I'm also assembling the drive electronics, so need to set aside some time for that before I get too old.

thx, Ken

[davo727]

Yeah I hear ya, But you asked so you recieved a solution Im doing a r45 clone from wholesale tool. Im probably going to go with a rolled SRT ballscrew from Nook Industries for my X axis. I get the impression that their quality may be a little better than rockfords rolled. Im going with the 1 inch dia, .250 lead and use 2 of the double circuit ballnuts and preload them against each other. SBN10472 ballnuts- I was quoted $137. ea and a SRT5005 1 in dia 48 inch ballscrew about $150. The ballnuts outside dia is 1.687 and will fit under my X table fine. So like $500 for a rolled type setup for the X. Ground would be closer to $2000.00. I have a couple of Big new surplus ground ballscrews for my Y and Z axis that I got a killer deal on. I am amazed that Industrial Hobbies uses those dinky 3/4 rockford ballscrews on there Z axis in there kits and cnc mills. Probably wont last very long fighting that giant heavy head up and down. Im gonna do my Z axis first and make sure my servo and encoder and pulley choices works good so I dont buy 3 of something that doesnt work.
http://www.nookindustries.com/ball/B...ailability.cfm
I am just starting on building a enclosure for the powersupply, geckos and electronics, next will be the upper bearing block for the Z axis and the block to connect the Z ballnut to the Z slide.

[kalbin]

Yea, I'm still worn out cranking the head up and down a few inches when I got the mill. I can't imagine using the mill even manually without a power assist on Z.

I was lucky to score another 32mm ballscrew to use on the Z axis and a 3/4 for my Y axis, so I've just got to solve the X problem. I hadn't really thought about getting Z running with the electronics before proceeding to X & Y, but you make a good point about using it as a pathfinder. All 3 axes will be very similar.

The IH mill is sitting in my garage with only the original X & Y screws removed so far. I've got to take it apart to move to my basement shop. Ugg! I guess the good thing is that I have the first screw I'll need in reassembly. Another piece of luck is that I have a RF-31 that I'll keep until I finish the IH conversion. Much easier than the partial reassembly I see some guys doing to make parts.

Ken

[davo727]

I have previously had my mill completely apart including all the gears out of the transmission and hope to only take the column leadscrew out only once more and reassemble with the ballscrew setup. Kind of a pain reassembling the leadscrew back into the coloumn. If I have to I can get the machinist at work to trim my Z ballnut mount to fit if necessary. I figure I can make it to fit the ballnut and leave it a little long where it fits through the column slot and connects to the Z slide and after I test fit it I can have the guy at work trim.030 or whatever off the face to align with the slide correctly so the ballscrew is perfectly vertical. I can add the lower screw support bearing later also. I am looking into the breakout board and electronics right now. Im leaning toward using candcnc stuff , I like there pendant control so I figure it would be best to use there other stuff to interface between my pc and the gecko 320s. With only one axis to start I will burn up less stuff if I goof up the wiring

[kalbin]

I picked up my stepper motors a couple of years ago when I planned to CNC by RF-31. I like the simplicity of stepper motors.

As I researched it more I decided to switch to the square column IH mill. Luckily I don't care about running the mill at 100ipm, so am hoping I have enough torque margin to run reliably. If not, I'll figure a work around by changing the timing pulley ratio or get bigger motors, or go to servos as a last resort.

I'm building my stepper electronics and power supply from parts and was lucky to get some motor driver chip samples from Allegro. Then I found the following site that sells blank PC boards to hobbiests. The only real challenge here is soldering on the surface mount ICs. http://pminmo.com/forsale/blankpcbs.htm

The electronics, computer interface and software should be the easy part since I'm an electrical engineer. The machining is a welcomed new challenge. Then I'll ease into some mechanical CAD program, not chosen yet....

It's still going to take me a long time to get anything up and running with this mixed in with other family and hobby obligations. Just building the stand & enclosure will be a sizable effort and cost....

[davo727]

Hi, The stand is easy. I made mine in a couple hrs. An enclosure is on my to do list. Here are a couple threads showing some other things I have done to my mill that are relevent to any square column.

7045mill lube mods and coatings
Some R45-7045 mill mods
My pneumatic counterbalance After I get the ballscrews in and have it running I will do a thread showing everything.