Spring loaded or Endmill for metal engraving?

[jTr]

Have started engraving for a metal fabricator -
He has a torchmate plasma cnc and hopes for an air operated engraving add-on sooner than later. Meanwhile, my bot gets the job for engraving his company logo.

Have completed first piece in aluminum - naturally wants to brand all items with his logo now, and rightly so.

Next piece: Stainless.
Um.....

Should I get a spring loaded tool, or a regular engraving end mill made for stainless?
Found the either/or options here:

Option1
http://www.2linc.com/engraving/tough_tip_1-4.htm

Option2
http://www.2linc.com/engraving.htm

What's interesting is their spring loaded versions are shown with RPM ratings, unlike the diamond drag tool. Client is expecting same engraved look I produced on the aluminum - don't think a drag tool will produce that milled look he's expecting.

And if that's not enough... Looks like I'll need a 3/4 shank if I go with spring loaded based on RPM's - don't think my 2.2 spindle operates lower than 8,000*, but also don't think they make an ER25 collet in the .75" shank for the higher rpm rated model.

*(HSD spec. sheet only shows max rpm of 18k, but am certain I've had issues trying to run it below 8k.)

Ugh - Any one have a simplified recommendation?

jeff

[Brady Watson]

Jeff,
You are starting to get into uncharted territory with the stainless. I think Onsrud or Amana make a bit for routing stainless, although the SB chassis may be a bit too flimsy for actual milling of stainless. The only advice I could give you is to make your best guess & try it for yourself. Experience is the best teacher I've found - and that's pretty much how I figure everything out.

There comes a point where you have to draw the line on what you are willing to produce on the Bot. Ask yourself if machining stainless is asking too much with the tool at hand and consider turning down the job or equiping your bot with a milling head or get another machine beefy enough for metal milling. Only you can decide this - Do the dollars make sense?

-B

[Bob Eustace]

Jeff our 2.2 goes down to 6,135 rpm.

[jTr]

Brady -
My metal buddy didn't seem to think this would be much of a challenge, as he's observed plasma tables outfitted with the air engraver spinning what appears to be nothing more than what could be chucked into any other rotating motor... From your response, we both may be underestimating the forces involved here? Based on the very shallow depth of .005, it doesn't seem as though I'd be straining the motor and structure that much(?)

Found an archive post from Adam Smith that indicated He was successful, though vaguely unenthusiastic:

http://www.talkshopbot.com/forum/showpost.php?p=102451&postcount=18

Looks like I'll give it a whirl, but I'll be spinning the $20 bit, as I don't think I'll be doing enough to justify the spring loaded version (famous last words).

Bob -
Thanks for that info - duly noted in my manual now!

Anyone else using the diamond drag engraver in a similar application? If so, do you think I'll achieve anything more than a lightly scratched surface?

jeff

[don_roy]

Hi Jeff,
I think what you will encounter is that tool life will be greatly diminished because of the high Nicole content in stainless steel. Sheet stainless is usually 316 or 304 stainless which both are nasty on tools even carbide.
Don

[Brady Watson]

Jeff,
The only advice I could give is to try it. That would be my response to the customer as well - then see how it goes & how you/he feels about the results. Yes, .005 is not quite the same as milling or profile cutting, but it's pretty dense stuff. I'm not sure I'd want to put my spindle up to that material for more than a few prototypes. You could put a mini-mill head on your machine, but it does take some engineering to adapt it. It is made for that type of work. Also, you may want to consider adding a 'coolant pan' so that you could add flood coolant without totally destroying your wood table.

Again...it really boils down to numbers. I would try milling with a .001" step down and see how that works out. A little WD40 isn't a bad idea - and PLEASE watch those little splinters - especially your eyeballs.

-B

[jTr]

Brady-

Thanks for the reminder - already 'done that.
In the interest of avoiding another scratched cornea*, I've really warmed up to the idea of a diamond drag tool for the simple fact it does not generate shavings. In fact, I should switch to it for the aluminum as well. Had a good conversation on this topic with a tech @ widgetworks this morning. I think it is the wisest choice.

Though I'd rather not invest a whole lot, $179 is cheap insurance for the safety factor. Easier on me and easier on the machine.


*No other injury has hurt as much as that scratched cornea -anyone else tuning in, please take heed. An aluminum shaving had settled on my face or hand. As I rubbed a tired eye while driving home, it found it's way in. Absolutely excruciating. :eek:

Thanks to all for the guidance. Will post pics when I get things working.

jeff

[Brian Harnett]

I don't have to much to add besides Canola oil works really well for a cutting lubricant I use it extensively on my manual mill.

It has a much higher flash point and does not stink.

[Xray]

Check ebay, widget is not the only option for drag bits, there are some very good USA made bits there, this is my personal fav
http://www.ebay.com/itm/DIAMOND-DRAG-ENGRAVING-BIT-1-4-DIA-STAINLESS-BODY-G0704-X2-CNC-MILL-/271296487496?pt=LH_DefaultDomain_0&hash=item3f2a87e048
This one is nice too http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=151136061106, both a whole lot cheaper than WW.

You are right, you will get more of an etch than an engraving with these, if you can live with that they are a superb tool. I have etched metals, marble, plexiglass and more, all with mind blowing detail, and the tips are tough to wear out, good for 100's of etches.

[tomwillis]

Jeff - the other decent coolant is Unist Cool Lube 2210. Doesn't have the properties like WD or oil based that will soak into spoilboard.
Tom

[bleeth]

I like "Rapid Tap". Works great, only takes a little, and doesn't build up.