Here we go again . . . MK4

**paulus.v** · 01-12-2018

Originally Posted by routercnc

It could be a couple of weeks away based on the little free time I have at the weekends and the long list of things to finish off.
I have been doing a bit here and there and filming short sections. See if you can spot the joins !

I'm eagerly waiting for your actual ali cutting video and hopefully some stiffness measurements.

I have a questions as I'm starting a new build trying to use some of your design solutions.

Have you researched or tested how the double beam gantry with the rails on top (80-100 mm more leverage) performs in the Y direction compared with the twisting of the popular single beam gantry?
You have mentioned at some point that mori seiki used this gantry design but I couldn't find any information. Could you point me where to find anything about it?

**routercnc** · 01-12-2018

Originally Posted by paulus.v

I'm eagerly waiting for your actual ali cutting video and hopefully some stiffness measurements.

I have a questions as I'm starting a new build trying to use some of your design solutions.

Have you researched or tested how the double beam gantry with the rails on top (80-100 mm more leverage) performs in the Y direction compared with the twisting of the popular single beam gantry?
You have mentioned at some point that mori seiki used this gantry design but I couldn't find any information. Could you point me where to find anything about it?

Here is the pdf link for the Moro Seki 5000
https://uk.dmgmori.com/resource/blob...0-pdf-data.pdf

This shows the box in box idea which was part of my inspiration.

I was worried about rails on top as they are further away but when they were underneath they were difficult to level plus would get chips and coolant on them or risk being hit.
On the sides made the gantry even wider which I didn’t like. When I saw the Mori rails on top and the beefy construction I went with that.

I have not measured the stiffness yet still other jobs to finish (build coolant system, skim bed, tram head, belt guards. . .) and other commitments are limiting workshop time but we will get there and get a video out when it’s done 😀

**paulus.v** · 01-12-2018

Thank you!

That dmg mori machine is a real beast. The blocks spacing on the Y rails is greater than the travel distance... And everything looks like cast iron. It is great that they put a lot of technical details and images in that presentation.

I never thought to put the rails hanging under the gantry with all that ram weight trying to snatch off the rails...

One more question, what is your gantry (rails) total length and travel distance?

**Zeeflyboy** · 02-12-2018

re tightening the retaining nuts, you can also dremel a little flat head screwdriver slot into the end of the ballscrew shaft and use that to hold the shaft still while tightening the nut.

Well I say "you can", I've never seen anyone else do it but it soother's probably a really great reason why not to, but it works for me! No more worries about damaging the important part of the screw vs not tightening it well enough.

**routercnc** · 02-12-2018

Originally Posted by Zeeflyboy

re tightening the retaining nuts, you can also dremel a little flat head screwdriver slot into the end of the ballscrew shaft and use that to hold the shaft still while tightening the nut.

Well I say "you can", I've never seen anyone else do it but it soother's probably a really great reason why not to, but it works for me! No more worries about damaging the important part of the screw vs not tightening it well enough.

Nice idea. I was thinking of flats machined on the end or on the last part of the ballscrew behind the housing but a slot looks good as it still supports all of the pulley. My other thought was that with the right equipment you can wobble broach a hex pocket into the end.

Paulus, rail is about 700 long and travel is currently 360. I could go a bit more but when the spindle is quite low nearer the bed it would hit the sides so have limited it to that.

**routercnc** · 22-12-2018

Episode 23 is now ready . . . . . finishing off ready for first real chips !

**Chaz** · 22-12-2018

Well done mate, certainly one of the best DIY builds I have ever seen. The attention to detail is immense.

In the cutting videos, the spindle bogs down. What power is it? Are you running full speed?

**routercnc** · 22-12-2018

Hi Chaz,

Thank you. I can't tell you how relieved I am to have finally 'finished' the machine (they are never truly finished are they?) and I can spend some time with the family again. I hope it gives some ideas and inspiration to others.

Yes, the spindle is a 1.5 kW Chinese spindle and I knew it would be the next limiting factor. I have other designs in CAD for various spindle options but they will have to wait for now. It works, and I can certainly make a few hobby parts with it.

It was running at around 12,000 rpm in the film (full speed is 24,000 rpm), with a 6 mm 2 flute 45 deg cutter for aluminium, with the approximate WOC and DOC shown on screen. Feed rate varied - the heavy cuts were around 700 mm/min and the finish cuts were around 1400 mm/min. I finished the tram and final build yesterday morning, and I basically had about 20 minutes yesterday afternoon to get some cutting footage before my 'time was up' so basically went for it. Although I didn't have much time to experiment I soon found the limits. I actually broke the tips off both flutes by being so aggressive.

Much to think about and reflect on over Christmas, but first a break !

**Clive S** · 22-12-2018

Nice to see it finally finished and making chips. It certainly is a big credit to you and I have enjoyed all the vids in the making.

**Chaz** · 22-12-2018

Originally Posted by routercnc

Hi Chaz,

Thank you. I can't tell you how relieved I am to have finally 'finished' the machine (they are never truly finished are they?) and I can spend some time with the family again. I hope it gives some ideas and inspiration to others.

Yes, the spindle is a 1.5 kW Chinese spindle and I knew it would be the next limiting factor. I have other designs in CAD for various spindle options but they will have to wait for now. It works, and I can certainly make a few hobby parts with it.

It was running at around 12,000 rpm in the film (full speed is 24,000 rpm), with a 6 mm 2 flute 45 deg cutter for aluminium, with the approximate WOC and DOC shown on screen. Feed rate varied - the heavy cuts were around 700 mm/min and the finish cuts were around 1400 mm/min. I finished the tram and final build yesterday morning, and I basically had about 20 minutes yesterday afternoon to get some cutting footage before my 'time was up' so basically went for it. Although I didn't have much time to experiment I soon found the limits. I actually broke the tips off both flutes by being so aggressive.

Much to think about and reflect on over Christmas, but first a break !

Ok, that makes sense. Go 24K, anything less has even less torque. I'd fit the largest spindle that you can in there, clearly limiting the machine. Congrats once again.