[Momentz]

Hi all you brains out there - I'm designing a 3mx1.5m rack and pinion router with helical rack and pinion drives. Any one done R&P before and have any words of wisdom? I'm nailing down the final drive details at the moment. First time through the movie is always interesting. I'm going to try and use as many "optimised" and organic designs as possible. Peter

I've used the 5:1 reduction from AliExpress with there helical rack quite a few times, I think it's great for a router application and have no problem setting it up to step at 0.01-0.02mm no problem with minimal anti backlash and zero with software intervention.

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[peteeng]

Hi Momentz - I was going to use 5:1 gearboxes on this one. So that's good - Did you use a spring contact for the pinion or just mechanically aligned? Peter

[Momentz]

Hi Momentz - I was going to use 5:1 gearboxes on this one. So that's good - Did you use a spring contact for the pinion or just mechanically aligned? Peter

I've done both.

First one was aligned and was quite the mission.

Second one I made a plate that the gearbox was mounted to, it to allowed it to pivot and be spring tensioned.

First one was harder to setup and took days to align the rack but ran faster and quieter.

Second one was easier to setup but does rack If run about 30m per min+ and is a little noiser because the mesh between rack and pinion is tensioned tighter.

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[peteeng]

Hi Momentz - I'm currently going with the alignment method vs the spring drive. I think a little patience is worth the result. Good to know it works well once done. The rack is in 1.4m lengths so I have joints in the rack how did you align them (correct teeth spacing)? small bits of rack? by counter meshing teeth? Regards Peter

[Momentz]

Yes I used a small piece of rack. But you can't use the same rack, you have to buy a small piece that's mirror opposite. The seller can send you a small piece for joining rack for a fee.

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[peteeng]

Hi Momentz - Yes I've read you can't use the same rack. With straight rack you can. Thanks I'll send a note to the supplier to see If they have mirrored rack. Thanks for the heads up. The forum comes through again. Peter

[peteeng]

Hi All- I think Milli will need a chip compactor as well. Peter

https://youtu.be/5z0YCTkhhss

[joeavaerage]

Hi,
got my new spindle today....after a long battle with NZ Customs (my fault). Really nice.....and worth the wait.

First impression is that the HSK32 toolholders are small, you can fit one in the palm of your hand easily. The toolholders supplied are ER20/HSK32.
I can see why it not necessary or even desirable to put an ER32 onto an HSK32 interface. The HSK interface is small enough I would be reluctant to fit a tool bigger than 12mm
for the sake of rigidity.

Can only guess that an HSK25 or ISO20 interface which are even smaller would give you similar concerns, ie the rigidity of the tool is questionable given the size of the
tool interface.

Depending on the sort of tools you want to use and in what material I would say most would be happier with ISO30, BT30, HSK32 or HSK40 or even bigger.

Craig

[joeavaerage]

Hi,
second impression....the tool change is silky smooth.

The Vietnamese supplier threw in a 2 position 5 way pneumatic solenoid so I have set it up and it works perfectly.

Could very easily have made a mistake though. The pneumatic cylinder that operates the tool release bar is double acting but has no spring return. When the cylinder activates
it presses the release bar against the tension of the bellvue washers. When the cylinder deactivates the piston moves but only as far as the bellvue washer return, and so the face of the piston is still
bearing on the release bar. The release bar rotates at spindle speed, and thus that contact between the piston and the release bar would soon generate friction....wrecking the whole thing.
Thus the piston needs to be actively retracted so that there is clearance between the piston and the release bar when the spindle is spinning. There is another air-port for this purpose.
I have no instructions other than some .jpegs....and those in Chinese. I could identify the tool release port, the seal air port and taper cleaning air port....but not this extraneous port that did not seem to do anything.
I now know that the extra port is to retract the piston. Glad I found that out prior to powering up and running the thing!

I do have a reasonable photo of the pinout of the three plugs
.
One is the three phase power input and earth, easy enough.

The 17 pin aircraft connector is the Sin-Cos encoder, and I have the pinout for that.....not that I really need it.

The last 12 pin aircraft connector is a little more troublesome. The pic I have does a pretty good job of the pinout. Two are for the PTC temperature sender, easy enough.
The remaining pins are for the three proximity sensors built into the spindle for sensing the presence/absence of a tool but also the state of the tool release. Clearly I need to thoroughly understand these later switches
to operate this thing properly. The truth table for the switch states are in Chinese. Hoping my Vietnamese supplier can help with decoding them. Either way I will have to experiment with then until I'm 100%
on them. The last thing I want to do is have the spindle start without a tool in it.....the tool retainer claws would suffer irreparable damage because of unconstrained radial movement due to centrifugal force.

At this stage I think I will build a small electronic board that senses the PTC temp sender. Such instructions as I have give a very good characteristic of the PTC temp sender around its critical temp. I need to build
a current source to measure the resistance and then have a threshold detect to Estop the machine should the temp go out of bounds. May in fact make the temp available as a continuous analog variable
to monitor spindle temp. This electronic board will also need some circuits to detect the prox switches and logic to ensure the VFD is cut-off if a fault is detected. I could use Mach4 to do that....I do have
half a dozen or so inputs to spare, but I rather think I'll have a small dedicated microprocessor board to handle temp and prox switches autonomously.

Craig

[peteeng]

Hi all - Been on a small trip to a machine expo and have had time to sort the 5 axis router I'm working on. I tried two ways to make it smaller and failed. Seems the 80mm spindle drives a lot of the geometry and even using 15mm rails did not help. It worked out close to my Scoot machine size so since I have a Scoot kit in stock I've based it on that kit. Has come together very well. Now to get to CAD detailing it... Peter

[G-Spot]

Hi all - Been on a small trip to a machine expo and have had time to sort the 5 axis router I'm working on. I tried two ways to make it smaller and failed. Seems the 80mm spindle drives a lot of the geometry and even using 15mm rails did not help. It worked out close to my Scoot machine size so since I have a Scoot kit in stock I've based it on that kit. Has come together very well. Now to get to CAD detailing it... Peter

What's your Scoot machine?

[RaderSidetrack]

What's your Scoot machine?

Here is Scoot's spec page: https://cncrouterkits.com.au/maker-l...le-cnc-router/

[peteeng]

Hi - The Scoot on that page is a couple of versions old. The main specs are the same I have extended the Z to 320mm lately. The page is due for an update. The machine base is now made from pressed metal steel not ply or MDF. The ply machines are very strong and stable. I like ply, it takes screws really well and can be made into thicknesses and shapes easily. 17mm of ply is same bending stiffness as 10mm of aluminium and its lighter and damper. Scoot is fully developed for production now. I visualised the B axis for epoch last night. It will have a small problem with the wires and plumbing sticking out of the top of the spindle interfering with the wall when the spindle is horizontal. I may use a square body spindle as this has the connections at the front. Or make a custom cap for the round spindle. Got to get the rest modelled to make decisions. But I'm happy with the B axis concepts. The devil is always in the detail however. Peter

E5 - B2 image - rear view of b axis assembly
E5 - B1 image - 3/4 view
E5 - B3 image - side view

scoot 5 - current structural kit for Scoot
scoot 1 - Scoot series 2 - now I'm at series 6...
scoot-S3 - recent Scoot build

[G-Spot]

Hi - The Scoot on that page is a couple of versions old. The main specs are the same I have extended the Z to 320mm lately.]

I like your use of top hat sections, they give you better rigidity than the same section in square tube, after they are mounted to whatever you screw them down to, box section means you have to mount your fixings within the width of the box section.

[peteeng]

Hi All - Although this is the Milli thread I'll chuck some of Epoch into it as Epoch is the proto Milli 5 axis mill. I have started detailing the tilting B axis so have looked at the plate that I'll mount the axis on. The channel is the weak link not the axis plate. I will make the axis plate stiffer with webs and add a cap to the I beam, then rerun... I looked at the axis plate in aluminium and steel. The 25mm steel plate (vs 25mm al plate) results in it only being 7% stiffer so the major deflection is in the flanges of the I section. The axis shaft is only 25mm dia and I thought that maybe the weak link but no. That's good. The rotary table axle is 40mm dia so that should be extra good ... The axis plate will be made from laminated aluminium I think...

Today I was asked to make a carbon fibre banjo tone ring. That sounds like some fun... Peter