An Enhanced X2

How is the project coming?
Any updates?

Ray
 
Hi Ray, I was just thinking I needed to do an update. I've had company. Some snow bird friends are on their way back up North and stopped here for a week. Beyond that distraction, I've had a terrible case of "You can't get there that way". I put the bearing holder together for the Thompson screw and mounted the table. There was a hard spot when I turned the screw. Same spot every turn. It didn't matter how I adjusted the nut in the saddle, it wouldn't turn freely. So I took the table off the saddle and turned the screw. The free end scribed a circle nearly an inch and a half in diameter. I played with the bearing block for a while, but the inescapable conclusion was that something is bent. Hours messing with the screw, surface plate, and indicators and I'm pretty sure that most of the bend is where the bearing surface meets the threaded part of the screw, but there is also distortion in the threaded part. It was an Ebay screw and I would have sent it back, but I made some modifications to the nut and the undriven end bearing surfaces. The seller didn't fall all over himself to replace it, and I don't blame him. I should have checked it before doing modifications. I know better.

So much for the Thompson screw. It goes in the resource drawer. I have a 1605 import screw on the Y-axis and some other things. I am okay with the performance. The problem is the integral mounting flange. The nut will fit in the recess I cut for the Thompson nut, but the table will not go on with the big flange sticking up. That flange was most of the reason why I got the Thompson. So with the Thompson out of the running, I can either buy a screw and nut from Roton, or do something about the import nut.

I'm cheap, so I attacked a spare (and short) 1605 screw from the drawer. The nut is hard. Way hard. It eats carbide without flinching. I don't have any ceramic or diamond inserts, so I attacked it with the grinder. My coarse wheel is #60, but it ground the nut faster than I expected. I put a plug in the grease port of the nut to keep out at least some of the grit. I now have a nut that will fit in the saddle without rubbing on the table. The present screw is nowhere near long enough, but at least I know that the nut can be fit without excessive grinding time. The ground down nut feels like it digested at least some grit. I'm going to take it apart and see if I can clean it out and put it back together, If I cant get it back together, I'll have to grind down the nut that comes with a longer screw. I'll pump the next nut full of grease before grinding it. That should keep the grit out better.
IMG_1379[1].JPG IMG_1380[1].JPG
Now I need to order a 400mm 1605 screw with machined ends and nut. But that will have to wait because I'm going to California and Washington next week.
 
That's really too bad to do all that work and then find the new screw is bad.

Have a good safe trip and things will look better when you get back.

Ray
 
OK I'm back in the shop. The trip to the coast was interesting, but I like our horrible Florida weather better. I have been occupied training the new puppy and getting one of the older dogs ready for rally competition, so time in the shop has been minimal.

The mounting for the latest X-axis ball screw is screwed. The recess was cut out for the Thompson screw that was bent. Not wanting to get a new Thompson screw or take a chance on another Ebay one, I got the Asian screw and modified the nut. That would be the one in the previous picture. I mounted the table and tried to get the screw and nut lined up with it. No cigar! The screw would tilt down towards the free end when the clamp screws were tightened. Metal removed for the Thompson nut was needed by the Asian nut. Since there is no way to put metal back onto the saddle without incurring a whole lot of re-machining, and a new saddle wouldn't help without just as much milling on it, I had to come up with a better way. I saw a picture of the nut mounted on the outside of the saddle. It entailed making a mounting block that would fit in the original nut pocket and extend outside the saddle to accept the ball nut. That still used the missing metal, but it got me thinking that I could just mount the ball nut onto the saddle directly. The ball nut needs to be pulled against the pocket rather than pushed against the back side. The back side is where the metal is missing. The original clamp screws are 6mm and the holes in the nut are 5mm. The ball nut is really hard. The is no reasonable way to thread the 5mm holes for the clamp screws, To top it off, the holes in the nut do not exactly match the saddle. But I am a metal butcher, capable of making many small pieces of scrap out of big ones, so I clamped the saddle to the mill and turned the 6mm threaded holes into oversized 5mm slots. Now I can use 5mm screws with nuts to pull the ball nut onto the outside surface of the saddle. The slots provide lateral adjustability to line up the table to the screw, and being oversize I get a little vertical wiggle. I put the whole thing together and the table, screw and saddle line up. I don't seem to need any more vertical travel, but I can slot the bearing carrier at the end of the table if I have to. Picture is of the saddle and nut. The bearing carrier is sitting on the table saw while the paint heat cures.

I still need to make a spacer for the driven end piece so I don't loose the 1.5" of travel that the nut takes up. The metal will be here in a few days. Mean time I'll procure a couple of grease fittings for the ball nuts and do final assembly on the Y-axis and saddle.
X-BallMount.jpg
 
No pictures. I greased the Y-axis nut, then mounted the saddle to the base. A little way oil and gib adjustment and the screw turned nicely. I then mounted the Y-axis stepper and fired up the control computer. I had to change the motor configuration because the new screw is 5tpi instead of the stock 16tpi. It moves! The stock screw never got over 6ipm before bogging down. The new setup will do 60ipm. Granted, there's not much load on it now, but I is going to be way faster than before.
 
Coming along nicely.
Good job resolving problems.
 
I machined the spacer yesterday. Tonight I lubed the screw, oiled the X-axis ways, and put it together. I still need to mount the X-axis motor. I'm not sure I can salvage the old motor mount. The new screw needs longer standoffs. It may just be easier to make a new mount.

I traversed the X-axis with a cordless drill. It was smooth with the OEM spec. travel. That is something the machine never did before. The ways are tight without restriction, but I expect them to wear in a little. I'll try my hand at writing a traverse loop when both motors are on. I'll let it traverse both X and Y for a few hours before I lock down the gib adjusters.

New travel for the table is 5.75" for Y and 9.25 for X. I could get 6" for Y if I wanted to diddle with nut clearances, but increasing the effective Y travel by 2.75" is a nice increase.
XandYaxis.jpg
 
I got side tracked worrying myself about the head setup. For years I have been coveting tilt and nod in a mill. I have tilt in my bigger G759 +/- 90 degrees. I have used that capability and it is pretty nice. It would have been nice to have the head swivel with a worm drive like a Bridgeport, but I probably couldn't have afforded it if it did. Nod would have been really nice on the G759 when I was cutting gibs, but there really isn't all that need for it.

the little CNC X2 doesn't have enough room to build in useful nod. Hoss put it in his Freak conversion, but he grafted two base casting together to get that much Y travel. I will leave nod for the next lifetime where I may be able afford a really big mill.

Rotating the head on the X2 would solve several problems with the tilt column design. Tram would be a lot easier and more stable. It would also be easier to strengthen the column if it didn't need to move about. I may be able to pull that off. I have added almost 2" of Y travel to the X2. I will need to move the spindle out about an inch to get it back to the center of the table travel. I also found when taking the head apart that there is 2" of dead space in the z saddle. That gives me up to 3" of space to rotate the head. I found a junky 4" rotary table that I had purchase in a misguided attempt to save money. The table is 2.5" high. It should be possible to graft onto the Z saddle and spindle casting. It has worm drive and clamping. It is pretty crappy, but the gears are good, so I could probably toss the tables casting and plate and put my own together.

I have been building a column model in Fusion 360. The saddle even goes up and down the column. I still have a lot of pieces to add to it, but I hope to be able to design the head modifications in the cloud rather than screwing up more stock.Column v5.png
 
The paint finally dried enough to finish the X-axis. The motors need to be calibrated, but that will have to wait until I get the head finished. The speed is approximately 50ipm.
Video will not upload. Probably too much storage space.
 
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