El Beast - Initial design phase, comments and critique welcomed!

[Zeeflyboy]

I assumed the same, ultimately there is a lack of stiffness and some small amount of backlash which would explain a small amount of surface imperfection. Its pretty much just a cosmetic issue and quickly polishes out.


Router - yes it would no doubt benefit from being a single piece but its too large for my machine to handle. It might be an upgrade that the new machine can make for itself later on.

[Zeeflyboy]

I treated myself to a couple of new toys recently, and thought I would share how I have been trying to tweak the machine into shape given it's had a lot of use recently and probably needs a little tune up.

For squareness, it's a bit tricky as the X-axis actually has a small bow in it on mine which makes square a moving target. I decided to take the centre of the bed as a reference as that's where I do the majority of my work and then use points 100mm either side of that to set the squareness. As it turns out between those points the X-axis bows towards the front of the machine by about 0.05mm but fixing that is more work than I want to take on given I'm building a new machine anyway and the deflection on this machine renders it somewhat moot.

Anyhoo, back to my method of squaring:

I treated the Y axis as my fixed one and the X will be knocked into shape by loosening the screws on one side of the gantry base (both side and bottom screws) and tactical use of a mallet to knock it into shape.

First I drilled two holes for some precision dowel pins along the Y-axis span, and used that to edge up my square reference which happens to be a thorlabs precision angle bracket from the new machine I'm building. A machinist square would be good to use too, but the one I ordered is sadly out of stock and I have to wait another month to get it...

Next up I put my dial indicator on the machine and ran to my first reference point (centre plus 100mm) and zeroed the dial. Run to the second reference point (centre minus 100mm) and then knock the gantry arm gently with the mallet until it reads zero. This will have slightly changed zero down the other end, so wash rinse and repeat. If you stop off in the middle you can check how straight your gantry is now as well.




Next up I really wanted to accurately tram the spindle, so I bought myself a tramming gauge. You could DIY one, even using just a single dial indicator if you wanted to save money, it's just quite useful to have the two as it saves time when knocking the spindle straight. If you do make yourself/buy one with dual indicators, its worth mentioning that you need to zero both indicators from the same reference point as this removes any issues with runout or different length indicators.

You want to make sure you are doing this from a level reference, so make sure you skim whatever surface you are doing it on with a fairly fine step over to get a nice flat surface to start from. First up I checked the angle in the Y-axis as this one needs to be shimmed and if you have done X first, you undo all your hard work when you loosen the screws to insert the shim material... mine showed the top of the spindle was leaning towards Y minus, so I loosened off the screws (be careful not to let the spindle drop) and inserted a small piece of shim material at the bottom of each side (the small bit of brass under the bottom screw).

Bit of trial and error, also noting that tightening the screws will change this reading so you need to check with the screws fully tightened up, but in the end I managed to get it to this point - each gradation is 0.001" so it's about 0.0005" out of square in Y across the length of the tramming tool. I'll take that!




Next up was to knock it into shape in X, so I loosened off all the screws except for the top right which helps hold the spindle in place. That one I just slightly loosened off to help the mount move but not so much that the spindle became loose. Use your surgical mallet skills to knock the spindle until both sides read the same and then for convenience I re-zero... as you tighten up the screws again it will move a bit, so just tighten then a little at a time and keep tapping it back into square until you finally have them cranked down nice and tight. On this one i Managed to get it to within what looks like a bit better than 0.005" or so (less than half of a gradation out).

It is then worth having a little spin the whole way round to make sure it's all still where you expect and that you didn't mess up your previous work in Y. So all said and done I believe if my maths is correct the spindle is now square to within about 0.006 degrees (calling it 0.015mm out across the 125mm span of the tramming gauge).




What will be quite interesting is that now that I have actually quantified the tram and the square, I will test it again after a few machining operations to see if it stays put or drifts.


Anyhoo, not saying this is the only or even the best way of doing things but it's just what I found easiest... it's all easily achieved in an afternoon.

[Chaz]

Awesome stuff. I need to do the same. I know I have a slight offset in the spindle mounting which I Can shim out but not yet done. It has minimal impact on parts but its not ideal.

[Nickhofen]

Nice method !!!

[Zeeflyboy]

Managed to crack out the back plate for the Z-axis today:

First fixture




Second fixture (I actually had two screws in the right side holes as well but took them out before I remembered to take a pic)




My replacement 10mm roughing bit arrived last week so I got another chance to use it after breaking my previous one with some stupid G-code. It very happily munches away at 14k rpm, 10mm DoC and 1mm axial engagement at 1500mm/min... makes short work of this 20mm plate as it's all done in two passes! Looking forwards to being able to up the feed rates and axial depths on the new machine I hope though.

Finished part:

[charlieuk]

I'm not sure why but I cant seam to see the pic's on the last few pages they have a little square with a x in it? anyone getting the same? the first ones still work fine. I get the same on booth my computers and my phone

[Chaz]

Works ok for me.

[mekanik]

Me to

[routercnc]

I can see the pictures

Nice work on the squaring and tramming.

[Zeeflyboy]

Charlie, if it's working for everyone else might just be that imgur was over capacity when you looked and the older pictures were cached... try clearing your cache and refresh.

Thought I'd experiment a little with the seals for the Z-axis. I have some red material on order so we can stick with the colour scheme but for now to dial it in I'm just using what I've got which is a nice orange!

So this is the part, I've designed it now so that it has a locking flange to prevent it from going walkies... it should just push into the top/bottom plates and wedge in place.






So off to the printer to try it out... I'm using a material called Cheetah by ninjaflex. It's a fairly firm but flexible rubbery material (shore hardness 95A) which is abrasion resistant, resistant to chemicals and pretty tough.








Here you can see the flexible rubbery nature:




Fit is excellent, but maybe just a smidge tight. I need to check it with the part actually held in the plates, but it may just need a very slightly enlargement of the interior cut out.