CNC Serving machine

[johnv]

Recently I finished the Mini CNC Mill which about which I posted some photos of the progress..
At the time I was just starting the standing rigging on the Mamoli Constitiution, and not happy with my first build efforts. Mainly with the seizing. I was making my own ropes and they were going quite acceptably, but the seizing was another matter.
Incidentally, I plan to use the mini mill to make the spars. I will post results soon.
Then I had a thought. I know that some modellers use a hand cranked apparatus to do the serving, and I wondered if I could make a CNC machine to achieve better results than I could manage using simpler traditional methods.
The electronics and MPG from the mill could be easily swapped over to operate the CNC serving machine.
So, after playing around with designs, and getting some useful advice from this site, I came up with a plan. Ordered various components, and waited for them to arrive before finalising the plans.
Some components were 3D printed, and some were machined. Many were purchased from China.
The mechanical parts of the machine are shown in the following photos. 800mm between centres. Nema 17 steppers. Electronics-Control box not shown here. See CNC Mini Mill thread.
When I have tested it, and made any adjustments I will show a video.

 

[Chestcutter]

This is an amazing project John. I will be very interested to see how it performs.
I would be concerned that the precision of the serving will be impaired by the lack of rigidity and predictability of the thread being served.
Your innovation and creativity are inspiring.
Michael

 

[Steef66]

I would be concerned that the precision of the serving will be impaired by the lack of rigidity and predictability of the thread being served.

I'm curious about this point to, because I did a lot of serving and there are many parameters to concern. Great if it works.

 

[johnv]

Time will tell.
The advantage of CNC is that very fine adjustment of the pitch of the serving thread is possible. Using a ball screw means that there will be very little backlash. And also the speed of the overall process can be finely adjusted.
The tension of the serving thread is less precise, but adjustable. There will be a learning curve.
Lateral movement of the rope might be a problem, but the groove can easily be remade narrower, if necessary, by reprinting it. (ps or making it in metal.)
I should have some initial results in a day or two.

 

[johnv]

First serving runs today exceeded my expectations. The machine worked close to perfectly, and after trying variations of the settings, and finding that I could push the machine speed to the limits of the Nema 17 motors, I did a 600mm length of serving 1mm diameter home made rope in about 2 minutes.
I can see a couple of areas to improve. The spool carrier groove needs to be smoother, and I will make a replacement top plate from metal, and send time polishing it. And I will design and make a V shaped extension carrier top plate to allow close access to the top plate thread hole for seizing close to deadeyes.

The first photo is 2mm x600mm rope, served with a several starts at different settings. The second photo is 0.9mm white rope served with brown Guttermann thread, pictured vastly magnified. I did take some videos, but the video quality is ordinary, and I will try to improve the video setup before publishing.
BTW, these ropes were rejects, used for first serving attempts because I was just experimenting and expected them to be thrown out. But with the serving, the poor rope quality is not so visible, hey?