[chich2]

Leeroy,
Well done!!!!!! Nice work on your new Quil.

Chich

[chich2]

Well Im back home for another week. Today I drew some plans and made a bearing block to house an angular contact bearing for one part of my Z axis. I want to keep this machine usable as a manual machine so I have made the new components fit into place where the standard thrust bearings were and make sure the bevel gears still mesh correctly for the knee hand wheel. (crank)

My saw is not running at the moment so I parted off a piece of 2.5inch dia high tensile 4140 bar. Then made the bearing block out of that. The bearing is a 7205B angular contact bearing. It will be preloaded against another 7205B using the standard nuts that retain the bevel gear. As can be seen in the sketch.

That's all I got done today but will be back at it tomorrow.

Chich

[chich2]

Thanks for the link Macona,
Today I machines up a few parts for the Z and Y axis's. For the Z axis I made some stepped collars and washers that go up hard against the angular contact bearings. The collars and washers space the spinning component away for the fixed race of the bearing. The spacer ring that sits up against the shoulder of the lead screw has the bottom angular contact bearing sitting on it supporting all the weight. Directly below it is where I mounted my toothed pulley to drive the screw. I do not want lubricant from the bearing getting onto the pulleys or belt so I made the bottom spacer with a lip seal running on the outside of it. On the inside of the spacer I machined a groove and installed an o-ring between the spacer and the shaft of the leadscrew.

The first photo is of all the new components sitting beside all the standard components. Both setups share the lead screw, bevel gear for the hand wheel and the 2 preload/lock nut's.

Second Pic is of all the new components on the lead screw.

No.3 is the Z axis drive pulley dialed up in the lathe ready to be machined.

4. Is the pulley with the Boss faced off.

5. is the pulley boared out and a slight tap fit onto the leadscrew.

6. Toothed pulley in position on Z axis lead screw. 2 M6 grub screws will later secure the pulley into position.

7. Is my pneumatic cylinder that I'll use to assist lifting the weight of my knee. In this photo I have cut one clevis eye off the bottom using a hacksaw. The cylinder has a 100mm piston and 400mm stroke from a 25mm rod.

8. I decided to do some work on the Y asis as well so I chucked the standard bearing mount and dialed it true.

9. I then bored out the Y axis bearing mount to fit 2 x 7203B angular contact bearings. The 2 bearings seat up against a shoulder inside the mount back to back for preloading. I faced the mount true to the axis in one operation so later when I attach the motor mount it will all be square.

That is it for today. I have drawn up a sketch for the servo mount and the cylinder mount an will start on that tomorrow.



Chich

[chich2]

Yesterday I removed the dovetail ram and spindle assembly like last time and then removed the knee. I placed the knee on some card board out in the yard and marked out where I need to cut away from the knee to fit the pneumatic cylinder. Once I cut out the bottom I then took several small cuts into the 25mm web that runs up the back of the inner knee. I did this with a 4" angle grinder fitted with a 1mm thick cut off wheel. It was just a matter of several light taps with a small hammer until the web pieces broke away. I did not want any stress cracks to develop into the good part of the knee so I used many cuts and only light tapping with the hammer. Once the web was removed I ground the web flat and smooth and then painted the bare cast iron.

The next step was to put the machine back together. Once I got the knee on I adjusted the gib and then lowed the knee onto a piece of hard wood. Next to go on was the Y axis dovetail. Now that I can secure the Y axis I set up my boring head and machined the hole that holds the Y axis lead nut deeper. I needed to do this because I made a much more solid retaining washer and a bigger bolt than the standard one. (There is a photo of it in a previous post).

I then assembled the Y axis lead screw, bearing mount and then tightened the antibacklash nut tightly to the machine. I placed a light preload onto the angular contact bearings and gave the Y axis a go by hand. I am very happy with how smoothly and easily it moves. Keep in mind that there is almost no weight on it at the moment so it may stiffen up a bit when the X axis and swivel is sitting on it too.

Chich

[macona]

Hey, I put up a post with my progress on the refurb of my mill:

http://www.cnczone.com/forums/showthread.php?t=28668

On the bottom there is a picture of the air assist ball screw.

[chich2]

Great thread macona. You have certainly got a great project there with your supermax. The air assisted ball screw is a good set up.

Keep up the good work,
Chich.

[chich2]

Haven't had a post in a while so here is an update on my cnc conversion.

I ordered a precision pressure regulator from SMC. It is acurate to the set pressure setting within 0.5% and repeatibility of 0.2%. I have made a mounting plate that the cylinder rod pushes on and bolted it in firmly to the under side of the knee. When I say underside I mean directly under the Y axis slide ways. Basicaly the cylinder gives me full stroke of the Z axis. I have cut a hole in the casting through the top of the coolant tank and sat the cylinder on the floor of the coolant tank. The floor of the coolant tank casting is about 20mm thick with some very heavy webbing so there is plenty of stregth there. The cylinder is set up to run parallel with the Z axis dovetail slide. I milled off some of the aluminium from the sides of the cylinder ends and I also milled quite a bit off the Z lead screw post. In the photo's you will also see half of the Z axis servo aragement coming together. You will see the servo pulley grub screwed with 2 M6 grub screws 90deg apart. I milled 2 small flats on the screw boss to take the pulley grub screws. I piped the regulator up with brass gas compression fittings and copper tube.

When it came time to try it out I backed the regulator off and turned on the air supply. I then slowly screwed up the pressure on the regulator and the handwheel on the knee became easier and easier to turn. Now when I raise the knee, the regulator fills the cylinder and when I lower the knee the regulator vents the excess pressure. The regulator has a very controll over the pressure in the cylinder.

Here are some pictures.

Chich

[chich2]

Today I made and installed a chip cover over my Y bedway. This should keep most of the chips and swarf off the beds. There are 2 photo's. A before and an after shot.




Chich

[chich2]

I have noticed that the HM-52 has only 1 gib adjusting screw on the knee. What happens is when you make a very small up and down movement on the knee you will see the gib actually stay's still for a very short moment as the knee moves, then the adjusting screw hits the jib and starts to moove it allong the dovetail. This leads to three things. First one is uneven wear. Second is that when the knee goes down the gib is slightly loose. when the knee goes up the gib get's slightly tighter. The third thing is that there will be a tendancy for the front of the knee (where the handwheel is) to drop down very slightly. It wont be much but the top of your knee will no longer be square to the colum of your mill untill you either travel the knee up or tighten the locks on the side of the slide.

I have fixed this problem by adding a second adjuster to the bottom of the knee. I had to chip away the bog filler from the underside of the knee and file it flat with a course file.


Chich

[chich2]

Here is the start of my servo mount. I milled some mild steel down to 20mm thick then bored a hole in 52.02mm diameter to house the bottom Z angular bearing and oil seal. I will try to show all this at a later date when it is all installed.



Chich

[chich2]

I didn't get much done on the machine today. I did manage to drill and tap some holes to mount the servo and I also drilled and counterbored the holes that connect the mounting plate to the mill.

Chich

[FPV_GTp]

hi

Nice work chick2

cheers

[chich2]

Thanks FPV GTp,
I am at work at the moment and will be back home this friday. I will be adding some new post's to this thread during the next week.

Chich

[chich2]

Here are some more pictures of my conversion. Next step was to mount the servo motor to the mounting plate. I made the servo mount to bolt securely to the flat surface I milled under there, back when I turned the knee over. I set the preload on the 2 angular contact bearings I put on Z axis lead screw (as shown in a previous post). Once this was done I then slid the servo mounting plate over the bearing clamped the plate tightly and marked the holes that secure the plate to the flat milled surface. I then removed the plate and drilled and taped the holes. This eliminates any binding issues caused by an incorrectly positioned mounting plate putting side load on the bottom angular contact bearing. Keep in mind that this mounting plate also doubles up as a bearing and lip seal housing for the Z axis lead screw.

The drive belt has to be tentioned, so the plan was to make the servo able to be slid back and forth allong the mounting plate on slotted holes. This was achieved by milling out 2 pieces of 25mm RHS box section. This can be seen in the first photo. The belt had to clear everything so if the belt did ever slap I had to make sure there was plenty of space for it to run in.

The rest of the photo's are pretty straight forwarward except for photo 5. Because the boss diameter on the small 14 thoothed pulley is so small and the shaft size on my servo is 10mm, I was concerned with how little wall thickness I had for the grub screw to hold into. Because of this I had to (very unwillingly) also add a grub screw hole in the cogged section of the pulley.(wedge) I cleared away any burs and made sure it sat down deep enough that it would not touch the belt when it runs. Guess I'll see what happens when it's running.

Chich

[epineh]

Looking good Chich, make sure you leave enough room for the tool changer!!!

Russell.

[chich2]

Khaa Haa! Yes russ I WILL!! Definately have to use one of your micro controllers for that one! I just read your thread and find it VERY interesting.

Good work!

Chich

[chich2]

Today I finished the Z axis servo mount. It was a matter of setting the pressure on the air cylinder and locking the Z axis dovetail clamps to lock the knee into position, then disconnect the Z lead screw form the machine and screw it down. Once the screw was low enough, then came re-mounting the Z screw pulley with it's 2 grub screws and passing a new belt over the screw. I then put it all back together and adjusted the preload on the Z angular contacts and mounted the servo and released the dovetail clamp locks. A quick belt tension up and we're in buisness. I wanted to see how it would go so I connected the 24volt servo to a 12 volt battery, quickly checked the air pressure to the cylinger and give the motor a quick tickle up with 12volts. BAM! up it went! Switch the wires over and down it went. Pretty crude way of testing but I could hear the precision regulator doing it's thing very quickly adjusting to the pressure rise and fall in the cylinder as the knee moved. Can't wait to see it going by CNC!!!!!! :banana:


Chich

[chich2]

Because my air asist cylinder goes through the base of my mill and sit's on the floor of the coolant tank, there is a good chance chips and swarf will get into the coolant tank. So I made an oil resistant neoprene cover to go over the gaps. This was firstly done by measuring it all up and cutting out a cardboard template. Once the template fitted, then the cover was cut out of neoprene.

Chich

[chich2]

Today I started the X axis servo mount. The first step was to make something to support the end of the X axis lead screw when the table is fully traversed to the right. In this instance the only support the screw has is the 2 anti backlash nuts mounted to the swivel. I have about 600mm of unsupported screw that needs to be held as the servo belt will be pulling sideways on the lead screw. I decided to firstly bore out the cogged pulley and slide it onto the shaft. This allowed me to see exactly where the servo motor would and wouldn't fit. Following that a few measurements of the rectangular box pipe that I have in the rack for the mounts, I came up with a quick scketch.

I cut a piece of steel, milled all the rust off it and milled it to size. Drilled the 2 bolt mounting holes and used my boring head to bore a hole in the plate for a slide fit on my steady bearing (6004 2RS). Bolted it on and gave it a go..... Good thing!

Chich

[chich2]

Today I continued work on the X axis servo mount. Firstly I cut 2 lengths of 150 X 50 RHS 270mm long (6" X 2" Rolled Hollow Section). The servo shaft needs to be parallel to the lead screw so an easy way to do this is to machine one side of the RHS flat and secure it to the machine and attach the servo to the same side. I removed the limit switch for the standard Hafco power feed unit as it is no longer needed. The table travel stops were removed as they are also no longer needed, and one X axis table lock handles removed (one will do). Next was to drill and bore all the holes and bolt it on. Hopefully tomorrow I will attach the motor and give it a test run.

Same old story, just hover your pointer over the picture thumbnail to get a description of the photo.


Chich