[Pat2000]

yes... thanks guy's

I think... thinking out loud again !!! that some form of metering device would be the best solution.

umm food for thought.

I reckon they could be made for very cheap me thinks the Peristaltic device - see piccy is not exactly complex

http://www.animatedsoftware.com/pumpglos/peristal.htm


thanks scott - somehow you just jogged my memory - the problem Gerry with just switching the flow of a fluid simply on and off is that you cannot reckon on the flow rate remaining consistant, the slight pressure would have to be very consistant, any build up inside the tube impedes the flow and perhaps? very important? the viscosity of the Glue/fluid, particularly glue would change with temperature, any build up/ restriction at the nozzle would again slow the flow.

so umm, extra axis - ok best, but whats needed is just an adjustable/preset speed motor or a series of pulses operating a diaphragm switched as per coolant command?

is just a vertical needle type outlet nozzle good enough?

I guess the outlet should be quite close to the 'deck'?

I'd want to lay say 0.5mm (0.020in) wide lines/bead

[cbass]

you cannot reckon on the flow rate remaining consistant...the viscosity of the Glue/fluid, particularly glue would change with temperature, any build up/ restriction at the nozzle would again slow the flow.

I think you are right on here. Viscosity will change not only based on temperature but also depending on how the material reacts to shear forces. Some materials thicken as they are sheared (moved) while others thin.

I would seriously look into using an auger-type pump controlled by a stepper/servo on a fourth axis (see image). This will give you precise control of pressure, which may be important given how small the nozel will be (.5 mm). The last thing you want is a pump that doesn't have the strength to extrude your material.

One thing I don't think you've mentioned yet is what kind of glue you plan on extruding. What consistency will it have?

[Pat2000]

Cbass , thanks I would have to study those Augers to understand the mechanism better, I'd prefer to make my own pump cos of cost.

the Idea I've been toying with is along the lines of what they call 'window clings' thats using window paint see piccys below, the out line (which will perhaps be all i want is made from a black line usually.

the Glue they use seems to be based on PVA type of wood glue (the white stuff!!) when it is semi-dry 1-2 hrs, the coloured infilling is added , thats of a runnier viscosity, flexable and semi translucent - its all done on a plastic backing and the 'cling' (rather like a sticker) is peeled off the backing and will self-stick on glass.

It is still All plans on the 'back burner' as they say.

chances are that I will use my cnc router for all kinds of other purposes lol!!

i'm pretty keen also to make a tangential knife

It would probably be OTT for me to use a stepper driven auger partly cos of running out of controlable axis, I'm using two steppers on my x axis so thats 4 axis spoken for - a rotary exta axis would almost certainly be one of my future projects.

so anyhow if say a small stepper - printer type can be fairly easily driven by a simplish electronic drive all I'd hopefully have to do would be turn it on & off? driving it at a pre-set speed?

I'd imagined that the auger was also or mainly used to mix 2-part Epoxy glues as they are 'extruded' is that right?

whey-hey boss mans says I can go in to work tomorrow and m/c parts for my router (on a days holiday) so :banana: I'm gonna fly me mill and rip-into a few parts!!

piccys from http://www.windowbutterflies.citymak...lyGallery.html

(site nothing to do with me!)

[andy_ck87028]

Pat

A different subject........

I also have been thinking of different tool head options for my CNC router and I have been intrigued about how to cut internal sharp corners; sharp sided internal right angle or, even more difficult acute angle internal corners. Clearly a router won't help.

I asked once before and broaching was suggested but that is no good for wood or plastic.

Looking at the vast array of power tools I was expecting to see a reciprocating file but I have yet to see one.

Any thoughts on how to fabricate a tool that would provide a solution to this need.

Andy

[Pat2000]

Pat

A different subject........

I also have been thinking of different tool head options for my CNC router and I have been intrigued about how to cut internal sharp corners; sharp sided internal right angle or, even more difficult acute angle internal corners. Clearly a router won't help.

I asked once before and broaching was suggested but that is no good for wood or plastic.

Looking at the vast array of power tools I was expecting to see a reciprocating file but I have yet to see one.

Any thoughts on how to fabricate a tool that would provide a solution to this need.

Andy

Broaching does work for plastic's particularly types like Delrin (Acetal) it broaches with a simple tool - would post details if you need piccys - I suggest you start a thread somewhere, However having said that it can be very fiddly to program - you'd basicly have to hand-code the broaching cycles - it's much easier to broach right through the material - to broach an internal 'blind' courner' is real tricky!!

I'm not much of a 'wood-man' but you've got the grain to contend with and so - very difficult.

you'll have to post details of what you propose to broach - how thick - what material - are there small details...

Pat

[Pat2000]

just found this on auger pumps - all a bit OTT (over the top) for my application but interesting for those following this - they reverse the auger slightly to stop/relieve pressure at the nozzle!

http://www.gpd-global.com/text/other/Back-end.htm

[cbass]

Cbass , thanks I would have to study those Augers to understand the mechanism better, I'd prefer to make my own pump cos of cost.

the Idea I've been toying with is along the lines of what they call 'window clings' thats using window paint see piccys below, the out line (which will perhaps be all i want is made from a black line usually.

the Glue they use seems to be based on PVA type of wood glue (the white stuff!!) when it is semi-dry 1-2 hrs, the coloured infilling is added , thats of a runnier viscosity, flexable and semi translucent - its all done on a plastic backing and the 'cling' (rather like a sticker) is peeled off the backing and will self-stick on glass.

It is still All plans on the 'back burner' as they say.

chances are that I will use my cnc router for all kinds of other purposes lol!!

i'm pretty keen also to make a tangential knife

It would probably be OTT for me to use a stepper driven auger partly cos of running out of controlable axis, I'm using two steppers on my x axis so thats 4 axis spoken for - a rotary exta axis would almost certainly be one of my future projects.

so anyhow if say a small stepper - printer type can be fairly easily driven by a simplish electronic drive all I'd hopefully have to do would be turn it on & off? driving it at a pre-set speed? ...

whey-hey boss mans says I can go in to work tomorrow and m/c parts for my router (on a days holiday) so :banana: I'm gonna fly me mill and rip-into a few parts!!

piccys from http://www.windowbutterflies.citymak...lyGallery.html

(site nothing to do with me!)

Pat,

As is often the case, economics determine the type of solution we end up with. The auger type pumps are not cheap. I'm almost positive of this. I just brought them up because I thought they are simple in principle. You may be able to find one from some other application that will work for you. Heck, you might even be able to build one. Its not unlike a meat grinder in design, but you already know that.

I'd imagined that the auger was also or mainly used to mix 2-part Epoxy glues as they are 'extruded' is that right?

I don't think they are used for mixing, at least not the one I illustrated. If it was, it would be much longer and would require knife blades in-line with the auger to ensure mixing. I think they rely on a seperate mixng machine before it is fed to the auger...

just found this on auger pumps - all a bit OTT (over the top) for my application but interesting for those following this - they reverse the auger slightly to stop/relieve pressure at the nozzle!!

Thats whats so cool about this design. It has very precise control as rotary motion is translated into linear motion. A lot of similarities to why ball/lead screws are so great.

Carlo

[Pat2000]

Pat,

As is often the case, economics determine the type of solution we end up with. The auger type pumps are not cheap. I'm almost positive of this. I just brought them up because I thought they are simple in principle. You may be able to find one from some other application that will work for you. Heck, you might even be able to build one. Its not unlike a meat grinder in design, but you already know that.



I don't think they are used for mixing, at least not the one I illustrated. If it was, it would be much longer and would require knife blades in-line with the auger to ensure mixing. I think they rely on a seperate mixng machine before it is fed to the auger...



Thats whats so cool about this design. It has very precise control as rotary motion is translated into linear motion. A lot of similarities to why ball/lead screws are so great.

Carlo

Thanks Carlo :cheers: Thats great... its all good info that we can pick up ideas from, I'm not sure how those augers work quite, I'll look into them if I get to it.. yes precise feed - name of the game thanks again