[arizonavideo]

It looks like yours has a lifting shock. I have a Weiss 30 but it came with no shock. Should just be two bolts.

[AVRnj]

It looks like yours has a lifting shock. I have a Weiss 30 but it came with no shock. Should just be two bolts.

Yeah, that is what I figured. I could not remove the column as the shock was preventing it, so I will have to get under the base to remove the bolts and hopefully that will allow me to get the column off.

Thanks.

[AVRnj]

I finally got the machine torn apart. Other than the head, the rest of the Mill is completely disassembled. The column was more involved than I thought because of the shock they use, but once I unscrewed it from the base I got the rest off with little challenge.

There are pieces all over my shop.

I also have started modeling the mill. I use an open source program called Openscad, since it is free and suits my background of a software developer. I doubt it is nearly as good as what others use, and it's taking me forever since I am not great at modeling, but I think it will payoff as I should be able to try things out in CAD before doing them only Mill.

Next up for me is to figure out my motors and electronics. I have been reading through Hoss's site to understand my options, but I am inclined to go more powerful for everything than the G0704 since this is a much bigger mill. While I don't want to spend any unnecessary money, I also will not cheap out on this. I am already spending a lot of money, and time on this project, and I don't want to let a few hundred dollars prevent me from getting the right solution.

I also need to figure out my measurements for the ball screws to order from linearmotionbearings on ebay. The Y and Z axis seems pretty straight forward to me since they only connect at one end, but the X axis is confusing to me since I need to connect to both ends.

I am hoping once I make my measurements, using Hoss's drawings as a guide and modifying them according to my mill, I can post them up and can get some help making sure they are accurate before ordering.

Here are some pics of where things stand:













Attachment 218024

Attachment 218026

Attachment 218028

Attachment 218030

Attachment 218032

[pippin88]

With the X screw, remember that the non-driven end (the free end) only needs radial support and should not be fixed axially. This means you don't have to get the length perfect. I use a bearing block that allows the bearing to move axially, and it's a couple of CM thick, meaning the length only needs to be correct with a centimetre or so.

[arizonavideo]

Don't go bigger with the steppers. 575 oz will be fine and you can direct drive all the travels.

I'm doing up some CNC kits for the G0704 this week and when I'm done I'm going to do a few for the Weiss 30 too. It really is a nice sized mill for most people they wont soon want a larger one.

The only place where you might want more power is the Z but you have the shock so it should move easy.

A early end plate for the g0704

PM-25 X axis stepper mount.MP4 - YouTube

[AVRnj]

With the X screw, remember that the non-driven end (the free end) only needs radial support and should not be fixed axially. This means you don't have to get the length perfect. I use a bearing block that allows the bearing to move axially, and it's a couple of CM thick, meaning the length only needs to be correct with a centimetre or so.

Thanks for the info. By any chance do you have a pic of that so I could see how it works?

I bought Hoss' DVD and it looks to me that he is fixing his non-driven end.

I am very inexperienced with all of this and I am not quite sure how the bearing block would be setup for this without the bearing falling out.

[AVRnj]

Don't go bigger with the steppers. 575 oz will be fine and you can direct drive all the travels.

I'm doing up some CNC kits for the G0704 this week and when I'm done I'm going to do a few for the Weiss 30 too. It really is a nice sized mill for most people they wont soon want a larger one.

The only place where you might want more power is the Z but you have the shock so it should move easy.

A early end plate for the g0704

PM-25 X axis stepper mount.MP4 - YouTube

AV, thanks for the tip. Makes sense. I will stick with the 575 for the X and Y.

[hoss2006]

Thanks for the info. By any chance do you have a pic of that so I could see how it works?

I bought Hoss' DVD and it looks to me that he is fixing his non-driven end.

I am very inexperienced with all of this and I am not quite sure how the bearing block would be setup for this without the bearing falling out.

The free end of the X uses only one bearing and is not tightly bound to allow for some axial movement.
Hoss

[AVRnj]

The free end of the X uses only one bearing and is not tightly bound to allow for some axial movement.
Hoss

Gotcha, thanks Hoss.

I did not catch that on the video, which makes sense because the measurements are done at that point.

[AVRnj]

I am hoping I can solicit some opinions and ask some questions from the people here with more experience than me.


Stand:

I definitely want to build a stand. I feel like the stand that came with the mill is just not sturdy enough, and I would like to build an enclosure for it. I would love to build one out of steel like some others have done, but welding is just not in the cards for me right now. I suppose I could use brackets and braces if needed. My inclination is to build one out of wood, very heavy duty. My fear is I plan on adding at some point a flood system, and I am worried that things will eventually run down and ruin the wood. My plan would be to laminate the top part of the stand where the mill would sit, so my hope would be that I could contain any spillage before it does any damage. Anyone have any opinions on this?

Double nut/motor torque:

I would like to use a double ball nut configuration on each axis to try to reduce backlash as much as possible. I have read many builds that have used them, and tried to do some research on the design, and I am a bit confused.

I understand the theory which is to use two nuts and apply a force in opposing directions so that each nut is directly on the ridge and remove all slop.

It seems to me that for all the conversions I have seen, the design is to use a Belleville washer between them with a pre-load, where the two screws are attached via bolts.

This obviously must add a lot of friction, and I would think that would mean I would need much stronger motors? Is this accurate?

I am wondering if anyone could chime in on whether they think this is a worthwhile exercise. It seems the cost is not very prohibitive, but there will be travel loss most likely and in all likelihood, the machine has other flaws such as the ways and overall rigidity that may make such a small difference not worthwhile. My inclination is to remove as much mechanical backlash as I can with whatever reasonable methods I can, but I would love to get other's opinions on this.

Thanks!

[arizonavideo]

You can double nut the X and Z without much problem without loosing any travel but the Y will have to fit under the casting or move the mount. You really don't need double nuts if you are using a offset ground nut with the right size balls.

I have one of the China ball screws here and it looks to have no backlash. I don't know if all are that good but a set of larger balls would fix any backlash.

To me is it a bit silly to use double nuts with a offset ground nut, half the balls will never see any load, just drag along. You would get less friction from only using one circuit of balls in each nut.

I did just make a mount for a double nut Z for the G704. It is smooth inside so you just screw the nuts tight and set the lock screws. All the weight sits on the nut face so you just have to make sure it does not spin. This is for the Roton style of nuts but two cost more than the China nuts. I'm doing it because I have a bunch of nuts sitting here and want no backlash and have room.

Attachment 218614

[AVRnj]

Arizona, thanks for the input, much appreciated. Makes sense.

[Fastest1]

Interesting use of a split clamp. That would work well on a Chinese nut or 2 preloaded.

[AVRnj]

Been playing around with the X/Y axis saddle and ACME nuts that came with the mill to get a better feel for how I need to design the conversion.

I have a few questions I am hoping some can chime in on, my plan is to use the plans I bought from Hoss as my guide, but use my own measurements. I plan on using the same style of bearing blocks and AC bearings, similar ideas on my ball nut mounts but modify them for my machine.

1) My x axis lead screw that came withe the mill has acme threads measuring 835mm and the X table is exactly 841mm not including the bearing mounts (33 1/8").

My plan was to order ballscrews that are 840mm for the ball screw threads, and the rest of the measurements according to the AC bearings, mounts, etc.

Does this size sound OK? I figure since I will only use 1 AC bearing on the non motor side, this will give me about 12-15 mm of clearance between the end of the threads and the mount, is that too much?

2) size. For the G0704, everyone seems to use 16mm ball screws for the X and Y and 20 for the Z. Should I stick with these, or try to go up to the 20's for the X and Y, and 25 for the Z? I am pretty sure I can fit the 20's on the X and Y if it is preferable, but I may very well have to remove some extra material to make that work. I am wondering if I won't be better off just sticking with the 16's and taking off less material. Any opinions would be appreciated.

As a side, I am starting to question using a second ball nut. I am thinking I may first try to repack them with larger balls, and see if the results are satisfactory, if not, i can always buy a second nut for each axis and re-design.

Thanks!

[pippin88]

You only need a radial bearing on the non motor (non fixed) end of a ballscrew. You need two AC bearings on the motor end.

[AVRnj]

You only need a radial bearing on the non motor (non fixed) end of a ballscrew. You need two AC bearings on the motor end.

Thanks Pippin88, Yeah, I got that from Hoss's plans, I am trying to follow them as much as I can with the bigger BF variant.

[pippin88]

Having fiddled with angular contact bearings for a while yesterday (trying to properly preload single row bearings with shims) they can be a pain in the arse.
Having done some further reading I'm now looking at double row angular contact bearings which are preloaded and also thinner. Much cheaper than matched pairs of single row angular contact bearings.

I'm looking at using 3001-2RS from VXB.com for my 1605 Ballscrews. They are only 12mm thick and are sealed (versus 16mm for the two single row bearings that come with the Ballscrews from chai, which come with external seals)

[AVRnj]

Having fiddled with angular contact bearings for a while yesterday (trying to properly preload single row bearings with shims) they can be a pain in the arse.
Having done some further reading I'm now looking at double row angular contact bearings which are preloaded and also thinner. Much cheaper than matched pairs of single row angular contact bearings.

I'm looking at using 3001-2RS from VXB.com for my 1605 Ballscrews. They are only 12mm thick and are sealed (versus 16mm for the two single row bearings that come with the Ballscrews from chai, which come with external seals)

pippin88, what conversion are you doing right now? I looked at those AC bearings on VXB and they look good. Also, how are you going about pre-loading the AC bearings? are you simply tightening the locknuts up against them, or is there something else involved?

[AVRnj]

I decided to slow down a bit and hold of on ordering. I read through a few other BF30 threads and see that the tolerances can vary from machine to machine.

I saw one use 20mm ball screws and another use 16.

I would really like to use the 20mm if I can do so without destroying my saddle and table.

My plan is use my 3D printer and try to design and make my ball nut mounts for at least my X axis, probably Y and Z as well before ordering anything.

I printed out some 1605, 2005 and some 2505 ball nuts yesterday and this gives me some good perspective on what will and won't fit.

I also may try to see if I want to pursue the double nut on each axis as well using 3d printouts.

I am thinking that the ball screws and nuts may be the absolute last thing I order, thinking I am going to make my bearing spacers and mounts as well, and when I have everything to my liking I will order the ball screws and ball nuts.

[pippin88]

I'm converting a TM20LV. It's the same size as a G0704 basically but the column mounting and base shape is much closer to the RF or BF series.

To take the play out of the single row AC bearings I'm using shims cut from soft drink cans. They are a pain the ass to make. I think I have them back to back with the shims between inner races (but I forget the correct naming of front and back)