Here we go again . . . MK4

**routercnc** · 23-09-2017

Originally Posted by Zeeflyboy

Awesome as always...

Just curious - clearly you are pilfering quite a few bits like screws from your current machine.... given that your current machine is clearly not half bad, wouldn't it make more sense to buy all new parts for the new machine, therefore keeping the old one operational and then selling it as a working machine on here?

I had to read that a few times - thought by screws you meant fasteners (!). OK, ballscrews, right . . .

Good question and yes that was an option but there are several reasons:
It might not look like it but the current machine is actually on it's last legs in several areas. It is on a knife edge for aluminium and I have to keep the feeds low, intervening regularly. Things improved a year or so ago when I replaced the Z axis rails (15 mm miniature rails) as these had developed free-play. But it has started chattering again and I think that 15 mm miniature rails are just too weak. The linear bearings on one leg of the gantry has also developed free-play which is probably not helping. Because I know the machine I can work around these and keep it dialed in, but I'd feel bad handing this onto someone else, especially a beginner.

Before final de-commissioning I intend to make a video of various cuts at different F&S and depths etc., showing the maximum performance and all the noises it makes. Also measure the stiffness of the machine one last time. Then (some time later) repeat on the new machine, and hopeful see some improvement.

I also re-built the bed some time ago to make it much stiffer. The new machine support rails have been designed to drop straight onto the old bed so I would like to re-use that and save making someone again. That much aluminium profile, especially the heavy gauge stuff that I have, is quite pricey.

So once the bed has been re-used, that only leaves the gantry (which I will re-use the 20 mm linear rails on as these seem OK) and the Z axis (for which the rails are earmarked for the sliding part of an ATC carousel as that is all they are good for). The various bits of plate will be used for future projects, including a few parts for the new machine once operational.

I have sold parts of earlier machines on ebay, but this time around I was happy to just migrate the good bits across to the new one and keep this hobby ticking along.

**Zeeflyboy** · 23-09-2017

That was a far more comprehensive reply than I was expecting - I thought I might get a "nah mate" lol.

Well certainly seems fair enough, Given what great results you are getting I never would have guessed your machine was marginal!

**routercnc** · 24-09-2017

DOH! Just looked at the thumbnail for this video and noticed that the corner plate is held on with cap head screws - they should have been button head screws. I watched the video again and the other 3 corner plates are held on with button head screws. Hopefully no-one noticed

**routercnc** · 07-10-2017

Episode 7 now ready . . . . lots of small jobs

**Davek0974** · 08-10-2017

Amazing, pure machinery porn.

The only thing I could add, based on the detail level in that axis is - where you have the grub screws for head tramming bearing upon the aluminium plate I might bore some recesses and let in some small steel pads, aluminium will give a little over time and your head could lose tram, especially when looking at the tolerances you are shooting for ;)

**routercnc** · 08-10-2017

Originally Posted by Davek0974

Amazing, pure machinery porn.

The only thing I could add, based on the detail level in that axis is - where you have the grub screws for head tramming bearing upon the aluminium plate I might bore some recesses and let in some small steel pads, aluminium will give a little over time and your head could lose tram, especially when looking at the tolerances you are shooting for ;)

Hi Dave

I think you are right and it will give over time. I had gone for big grub screws and lots of them to spread the load but aluminium is soft. I could do with washers without the holes - don't fancy turning them from stock. Anything you know of that's available?

**Davek0974** · 08-10-2017

Don't know anything off the shelf, might just need some 10mm rod and part some 4-5mm discs off.

**Clive S** · 08-10-2017

I like the approach to make the pre-load in the screws with two nuts.

**routercnc** · 08-10-2017

Dave,
OK, will have a look at what I could do there.

Clive,
Cheers, I don't know if this is going to work but it's worth a shot to see what happens. I'm only going to fit them to the Y axis to see how it goes. I have some spare nuts to do the X axis as well.

I have some belleville washers on order in case the spring washers don't work out. It will really come down to how much speed I loose on the steppers due to the extra load causing them to stall out earlier.

**routercnc** · 30-10-2017

Still working on the next video installment - some issues to be resolved so will be a while before ready.

In the meantime I'm working on the lower cover plate and decided it would be great to use Zeeflyboy's seals (shown fully retracted Z axis):