1st Build, Second machine

[m.marino]

Okay,

Let's see if I can get these files up properly.

Sorry that they are jpeg's as it would not let me load the .dwg or .iges file format. That is the bracket I designed to go with a dumpsterCNC anti backlash nut for a 12mm trapezoid leadscrew. Clearance is only 40mm in height. Any opinions???

Also Checking on available box Aluminium in the area but is looking like I have a really good source of off cuts (some over 2 metres) of 12mm Aluminium plate. Any and all views would be greatly appreciated.

Michael

[m_c]

If I've worked it out right, all that's needed is a bit angle, with four holes on one side for bolting to the cross brace, then on the other side a big hole (21.5mm) for the anti-backlash nut to pass through, with another two holes for bolting the nut on via the flange (having looked at the dumpsterCNC site, I'm guessing you're for the 25mm cut-down flange option?).
Something suitable could be made with a pillar drill, a couple drill bits, and a hole saw.

Regarding mounting the nut, I'd use a couple nyloc nuts with plain washers to spread the load. I'd also put the bolts through from the alloy side, tighten them into the flange, then use the nylocs to make sure the bolts can't move.

[Jonathan]

Something suitable could be made with a pillar drill, a couple drill bits, and a hole saw.

Yes, I was thinking that so thought there must be more to it.

[m.marino]

The idea was for it to be of a single piece of either angle or mill from block. That should insure the rigidity of the piece. As far as the Aluminium is concerned drop me a line folks and will try to arrange something. I need to be going down there any how to see if they have any square tube stock that could be drilled and bolt together for the new frame.

Looking through old threads hear for sources of materials and looking like I just might be able to get both up and running (which would be great as I have work to keep two to three mills going for the next month and a half at least).

Still building and still kicking.

Michael

[m.marino]

Okay,

Ordering the 2 - 12m anti backlash nuts from Dumpster. One for the 12mm on X axis and one for the Y axis. Looking at getting a piece of 12 Aluminium to go across the gantry to add a bit of ridgeness and boring out the section of Z axis that rides on Y so that it will accept 16x20x30 mm Oilite bushings to it and most likely do the same to the bushings on the Z itself to get less flex and better wear as the current bushings are looking to need replacing and with less then 300 hours cutting time on the machine, I think upgrading if possible would be the wise way to go. Only need to drill out the 30x120 extrusion to accept the new bushings.

Also putting in new Bearings on the end and switching to stainless steel with rubber seals and see how that goes. Still working on the new machine and have bought the Z ball screw from Gary at Zap and just need to earn the rest of the money to buy the parts (also need to draw up my ideas and let you folks have a field day with them).

Anyway take care folks and have a great day. More information as it happens.

Michael

[m.marino]

Okay on a space and accuracy level, are using Oilite type bushings worth doing over linear bearings? This is doing improvement and part rebuild of a Marchant Dice MDL-TR-2 gantry router. I am building a new Z for it so that I can mount the A axis I have for it on board and starts being able to cut both sides of an item and let the machine do the flip. Going to linear bearings takes about 30mm of travel out of Y due to the required widening of the Z body to allow for the bearing blocks. On the other hand it will increase smooth play of travel.

So, any and all input as I am really up in arms on it and it is bottle necking this point in the design structure.

Thanks for all the input you have given.

Michael

[JAZZCNC]

Okay on a space and accuracy level, are using Oilite type bushings worth doing over linear bearings?

Hi Micheal,

Dont do it.!. . They dont even compare in the slightest. Even with the best alignment and boring, reaming etc they still dont hold candle to linear bearings and will wear far quicker, far too much hassle IMO.

If you do go with linear rail drop me a PM before you buy I probably can help.?

[m.marino]

Okay with the advice given and working in ViaCAD to get things set up would like folks opinion of the following set up for a Y Z axis set up.


The dimension marks are left over from getting the height right from the table surface and still having space for the 4th axis.

So please folks opinions. This is not complete. The Y is a little to long (was learning how to download files from Hiwin, great set up they have) and the screws on the Z and the Y are yet set in, nor is the anti back lash nut for Y (it will be between the two rails).

There are 4 carriages holding the Z axis to the Y even though you only see 2.

opinions please.

Michael

[JAZZCNC]

Put the rails on the front plate and the bearings on the back plate. This way the rails help stiffen the front plate.
The carriages then go low on the backplate and it makes for a very stiff z axis with max support where it's needed.! close as possible to the cutting end.!

Edit: Also if you pocket the bearings into the back plate slightly you regain some of the lost stand off from gantry. Also you can use one of the pocket edges as a datum ref point for alignment of the bearings. If you also do the same with the rails into the rear of the front plate, (but not quit as deep) this as the same affect and also another datum ref edge.
The net affect of both brings the stand off from the Y axis down slightly and also creates accurate ref edges to work from which are essential for setting up profiled linear rails correctly.

Hope this makes sense.! If not just ask and i'll try to explain better.

[Jonathan]

Put the rails on the front plate and the bearings on the back plate. This way the rails help stiffen the front plate.
The carriages then go low on the backplate and it makes for a very stiff z axis with max support where it's needed.! close as possible to the cutting end.!

If the rails are contributing significantly to the stiffness of the material you are using for the Z-axis then that material should be made thicker/stronger. Still definitely put the rails on the front plate, but primarily for the second reason - the supporting carriages are closer to the bed.