My engraving nose

[jonesthesoftware]

HI Guys
I'm following this thread with interest because engraving on my CNC is a pain because of the variations in paint thickness, material thickess and finding a good flat surface to work off. However I can't quite see the logic of suspending your spindle motor and all that metalwork and moving it further away from the ballscrew (which is the basis of accuracy in all CNC machines), and introducing more potential areas of lateral movement i.e bushes and bearings. This still leaves the basic principle of a presumably ball shaped tip actually resting on the material. Surely you should be looking to minimise the hardware involved which is why I've gone for a simple spring loaded collet extension. The principle is the same( ball end on material but there is only 1 point at which any play can be introduced and that is the point where one part slides into the other. What advantages does your designs have over my simplified version? What materials are you guys using as the "ball end" that sits on the material? I am not criticising your designs in any way but looking to improve my own engraving. I've had 2 floating collets made so far(at £120 each) and frankly the quality of the lathe work was rubbish the sliding fit wasn't close enough in tolerance and the smoothness of the Teflon ball tip wasn't good enough it left scratches on my paint.
kind regards
geoff

[Hessel Oosten]

My only question is , where marked in red are there some type of bearing or bush in there or just a very snugg fit as this part Must not have any play other wise it would affect the engraving right?

Rich,

Don't know, since this a a pic of a commercial one that I have never seen in reality.
BUT, the ONLY difficult (alias important) part of making this yourself, is the need of very tight fit in X and Y direction, BUT the very elegant/smooth going .. in Z direction of the sliding parts.

Glad you are now on your way !

Hessel

[Hessel Oosten]

Hi Geoff,

1. I think everyone agrees with you that all should be as tight as possible near the center of the main/first z axis. The fluttering "thing" a kind of second z axis ..

2. May be the differences of several of these things with your spring loaded .. collet is that that "thing" gives pressure on the surfce with risk of scratching ?

3. In the majority of other designs a mechanism is build in to reduce (!) the pressure on the material. In Wendy and my machine by pulling-springs (reducing the weight of the whole z axis and motor) and in the other desings (see pic in previous message) by a pressure-spring, nevertheless giving also pressure / weight reduction.

I can send you (if you wish) the same bunch of info I did send to Rich ?
Could be that it is overkill with all your technical knowledge.

My nose is teflon, smooth and soft, with some carvings to blow the dust from it (for scratching in pcb/copper and for not lifting the nose by dust in other cases).

Hessel

[riche543]

Going too order some of these. http://item.mobileweb.ebay.com.au/vi...d=300553706107. 4mm bushes will see how the tolorance is with them, it's harder to find the 4mm rod to go with them,might work for that design of the float. if anyone knows where too get the right rods for these please let me know
Cheers
Rich.

[jonesthesoftware]

Hi Hessel
I can see that the "weight reduction " by springs will work just fine, it's just I had reservations about the distancing of the cutting tip from the axis of movement and any play in the slides. Even 1 or 2 thousands of an inch of movement at the bushes/slides translates into several or even tens of thousandths at the cutter tip which is enough to ruin engraving.
I'm afraid I was unlucky in not being able to find a good quality engineering shop on 2 occasions to make my floating collet and I'm very reluctant to pay a third time.
Thanks for the offer of the info though but I won't be building that type of floating head in the forseeable future. I'm managing to get good engraving results at the moment by careful choice of materials and a good flat board to place materials on. I also have a "clock gauge" which I run over the material first to check flatness then put packing underneath for best results.
kind regards
geoff

[Hessel Oosten]

I also have a "clock gauge" which I run over the material first to check flatness then put packing underneath for best results.

And the best securuty without nose is of course to engrave only 2-4 letters at the same time.
I try 0.05 mm amd look, add 0.05 mm and look again. In most cases than, it's done.
In between these I rub the engraved channel with my finger, so rubbing the burrs into the engraved channel. The second pass they will be removed and the channel is again clear and the burrs are gone.

h.

[riche543]

Hi All

Well finally got round to finishing new cnc & got the engraving Head & nose done, its been a long time coming but glad i didnt cut corners , test results are great & no more too deep or completely miss opposite end because material or table isnt pefectly flat .
Also im using Compressed air to clear chips so thought i might as well use it for keeping the nose clean while engraving too, (Hole too the left of the white nose)
Also posted few more pics of cnc in my albums.
Thanks for the great replys too all my questions regarding this. Heres a few pics
Cheers
Riche.


157_800x598.jpg160_448x600.jpg170_800x598.jpg168_448x600.jpg165_800x598.jpg

[Hessel Oosten]

Riche !

Looks GOOD +++, and a solid construction too !
The font type does not seems to be "aviation related", so we want to see it (mainly) in Futura MdBt in next messages .....,

Hessel

[riche543]

Thanks Hessel
So pleased its finished & working well.
Talking of fonts ive been trying too hunt down Futura Md BT in a single line font or one that is virtually the same as Futura Md BT but single line? Reason i say this is wouldnt it engrave quicker if the toolpaths for engraving were single line , ?
Cheers
Riche.

[Hessel Oosten]

Hi Riche,

Sorry for late response; did not see the forum for some weeks.
Single line fonts are expensive and difficult to find.
I never found usable ones for us.

BUT, double lines are only a few seconds slower...

Use the internal spiral pattern, e.g. with a 0,3 or 0,2 mm mill.
In our lettering, which is so small, there is nearly place for a up and a down pass of the cutter. In that case the space is already filled. In e.g an "R" or a "B" at the narrow places there is only space for one pass.

Hope this helps,

Hessel