More upgrades to my HossG0704 Phase2, linear rails

[skyguynca]

Ok here is the 90% complete model, saved the files as jpg's so you can see how it is coming.
Tonight I start on the cabinet that will enclose the mill for flood cooling and support the mill giving more rigidity for the increase travel on the XYZ axis

David

Don't forget go to Hossmachine Homepage and g0704.com and get Hoss's DVD or Downloads for some really good tools, mods to you mill and console design. Best out there I think.

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[skyguynca]

Oh, and I am removing the old Roton ball screws and nuts, nothing wrong with them, just got a really good deal on the C7 1605 ball screws and nuts.

[pippin88]

The big head spacer will result in reduced rigidity.

The Z plate / head spacer is a weak point. I would have bracing like I've crudely drawn:

[skyguynca]

Yep, did the bottom one, it is in the new pictures along with a counter weight to help with head dip. There is also a counter balance weight only 70% of the counter weight.

[lcvette]

If you're going that far out with extension, you might be better off adding a second base and column and making a bridge type design to re-stiffen it up and still offer the increased Y travel.

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[skyguynca]

I thought about it, but it is only a 5 inch extension, twice what Hoss did but stable. With the way I have installed the counter weight and along with the support from the enclosure it should be fine.

If I were to make it a Bridge type, I would be better off making all the parts new. Which is the next project. A machine almost 3 times as big, bridge type that will use 35mm rails and blocks, with Y 60in, X 40in and 30in Z....it is going from drawing on paper to Solidworks when this one is done and running, need this finished to make the parts for the next one.

David

[lcvette]

Also, you have alot of cantilevering going on with the bearing blocks, you will need to use flange type bearing blocks on one side of the saddle for access to the bolts and you should stack the cars on top of each other (with the same plate between them still), it will help better tie the transferred load to the saddle. Also a very stiff base plate under the tied together bases should be used as you have put the downward cutting force directly on top of the mate section. This means all the stress is targeted into fasteners at that point which have substantially lower cross sectional area than the base cross section. Looks like a fun project, but it will need some tweaks or you may be disappointed with the results when you start cutting.. gonna be some big flexing going on that will induce chatter.

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[lcvette]

I thought about it, but it is only a 5 inch extension, twice what Hoss did but stable. With the way I have installed the counter weight and along with the support from the enclosure it should be fine.

If I were to make it a Bridge type, I would be better off making all the parts new. Which is the next project. A machine almost 3 times as big, bridge type that will use 35mm rails and blocks, with Y 60in, X 40in and 30in Z....it is going from drawing on paper to Solidworks when this one is done and running, need this finished to make the parts for the next one.

David

I didn't see the enclosure..., But it will need to seriously stiffen up the column. I have a 3.5" spacer and can tell you it's too much, at least if you want to make square parts. That's alot of weight hung way out on a skinny little column..lol. Believe me, when side cutting in the X axis, there will be chatter.. the whole head will start bouncing from the tool on the part.. and it will not be fun.. true statement from experience.. Believe it! Run an FEA on that setup in solid works and check the difference between the stock throat depth and your proposed throat depth. You will be amazed what each 1/2" starts adding the further out you go, it starts compounding as the spindle centerline moves further away from the column face because you're increasing the torque applied at the z axis slide to column connection.

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[skyguynca]

yep, I did run the FEA. I made some changes to the column. I added some .25 2x2x3 steel channel on both left and right sides and on the rear wall internally, still enough room for the ball nut. On the back of the column I added a 25mm single rail down the center, the counter weight to handle the head dipping rides on it connected rigidly to both sides of the head extension. The mill is mounted to a L assembly made from .5 wall 8x8 square steel tubing. Another 25mm rail and block assy connect the railed counter weight to the frame of the L assembly. It some of the tests I have ran it stiffens it up quite a bit. Essentially it has the same moment as the head and extension and prevents the column from twisting.

I am looking at reworking the table assy. I was not worrying about chattering with all the rail blocks always under the spindle, and each is a 20 mm assy, they can more than handle the cantilever loads according to THK specs. The problem is the flexing of the .75 base plate. If I make it any thicker it will take away too much Z height. So I have been thinking of making it from 1 inch plate and pocketing out ribs in the bottom of it except for the bearing block mounts. Each pocket at .5 deep with .25 walls, I loose alot of mass I want to keep, but it also stiffens up the plate alot.

That is why solidworks is worth the price. I make changes and test it more. The head extension is rock solid, the column with mods can handle the length. but the machine base and the Y base are what is causing the most problems. It seems adding mass and parts is getting to the point to where it is alot of parts and I am loosing the extension I am working so hard to provide

David

[lcvette]

yep, I did run the FEA. I made some changes to the column. I added some .25 2x2x3 steel channel on both left and right sides and on the rear wall internally, still enough room for the ball nut. On the back of the column I added a 25mm single rail down the center, the counter weight to handle the head dipping rides on it connected rigidly to both sides of the head extension. The mill is mounted to a L assembly made from .5 wall 8x8 square steel tubing. Another 25mm rail and block assy connect the railed counter weight to the frame of the L assembly. It some of the tests I have ran it stiffens it up quite a bit. Essentially it has the same moment as the head and extension and prevents the column from twisting.

I am looking at reworking the table assy. I was not worrying about chattering with all the rail blocks always under the spindle, and each is a 20 mm assy, they can more than handle the cantilever loads according to THK specs. The problem is the flexing of the .75 base plate. If I make it any thicker it will take away too much Z height. So I have been thinking of making it from 1 inch plate and pocketing out ribs in the bottom of it except for the bearing block mounts. Each pocket at .5 deep with .25 walls, I loose alot of mass I want to keep, but it also stiffens up the plate alot.

That is why solidworks is worth the price. I make changes and test it more. The head extension is rock solid, the column with mods can handle the length. but the machine base and the Y base are what is causing the most problems. It seems adding mass and parts is getting to the point to where it is alot of parts and I am loosing the extension I am working so hard to provide

David

If you stack the cars on top of each other your stiffness will increase, the plate holds them aligned and positioned, but if the stack is connected you are removing the need for the thicker plate as the load transfers from rail to rail and the then to the base and table connected to the rails.

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[skyguynca]

I am shortening the head extension back to 2.5 in. I still plan on putting the stiffeners in the column. I loose a couple of inches in Y because of the width of the plate needed to give the table rigidity and stability. I loose 4 inches in Z because of the stack of plate, rails and bearings.

So with the Hoss mods with gibs installed I was able to increase travel. I gained 3 in Y so it went from 6.875 to 9.875, and 5 inches in Z going from 13 in Z a total of 18 inches, and X was 18.875 .

Installing the linear rails puts Z at 13.5in( back from 18), Y at 9 .25in(only a loss of .625) and X at 19in (I actually gained .125).

I think I have the rigidity problem licked. I will post the new pictures later, probably tomorrow. I will start cutting off the dove tails this weekend, and cutting the parts for the base extension.

However next week I will be welding up a frame assy for a big surface grinder to smooth and level the mounts for the linear rails. I have to finish the grinder before I can finish the upgrades.

More to come
David
San Jose,CA

[lcvette]

I am shortening the head extension back to 2.5 in. I still plan on putting the stiffeners in the column. I loose a couple of inches in Y because of the width of the plate needed to give the table rigidity and stability. I loose 4 inches in Z because of the stack of plate, rails and bearings.

So with the Hoss mods with gibs installed I was able to increase travel. I gained 3 in Y so it went from 6.875 to 9.875, and 5 inches in Z going from 13 in Z a total of 18 inches, and X was 18.875 .

Installing the linear rails puts Z at 13.5in( back from 18), Y at 9 .25in(only a loss of .625) and X at 19in (I actually gained .125).

I think I have the rigidity problem licked. I will post the new pictures later, probably tomorrow. I will start cutting off the dove tails this weekend, and cutting the parts for the base extension.

However next week I will be welding up a frame assy for a big surface grinder to smooth and level the mounts for the linear rails. I have to finish the grinder before I can finish the upgrades.

More to come
David
San Jose,CA

I think that's a smart move.. and you will be glad you opted not to extend out too far!

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[skyguynca]

OK, so here is the latest version of my conversion to linear rails for my G0704, along with the enclosure and support frame. I did have to make the head extension just a bit longer, 3.5 inches, but it you look at the JPG's you will see the column is tied into the frame structure (which is not complete yet) to handle the loads of the long extension.

As I get the 3ph AC motor, belt drive and VFD dimensions I will add those to the drawing. I still need to make the sheets that will line the inside of enclosure. I also plan on using the original G0704 stand under the Mill, with legs at each corner to make the frame/enclosure rock solid.

David M.
San Jose, CA

[DubMFG]

There's a certain point where you start applying lipstick to a pig here IMO.

[DRock]

That enclosure is a bit overkill, you don't need any of the three middle horizontal sections for starters.

Why did you choose to make it so overly complicated?

[gcofieldd]

You should checkout what this guy is doing: