Rotary Engraving Question- Brass

[Scott Shepherd]

I've avoided engraving polished brass for years because I could never figure it out. What always happens to me is that the brass chips from cutting get caught under the nose cone when the Z lifts up and moves to the next feature. Then it drags that chip all around the nice polished finish and ruins it. I'm using a Xenetech rotary machine and it's got the nose cone with the vacuum pickup on it. I got a call from a customer wanting me to explore being able to do this type of work. I've always refused it or either subbed it out. My sub source has gotten so expensive I can't sell it for what I pay for it, much less what I pay plus a profit for me, so that ship has sailed.

I've got all the machines I need to do it, I just seem to be apparently missing some critical step.

I removed the vacuum nose cone and replaced with with a leaner, meaner nose cone and thought it would work better. I put transfer tape on the surface that will be engraved to protect it, but what happens is as it's cutting, it's moving tape around, like around the letter "N" and such. So now that it's lifting that transfer tape, the nose cone senses that bunched up tape and cuts shallower. So my effort to protect the work ends up causing the depth to get all messed up.

We have the old Hermes Pantograph and I hate to drag that thing out, but I'm getting close to it. At least there, you can control all the things that would cause a scratch.

Any tips or pointers on how to engrave polished brass on a machine that uses pressure on the nose cone?

Thanks in advance-
Steve

[bruce cain]

Depending on the size of the job, sometimes I will leave the nose cone off, or leave the film on the brass, or use a burnisher tool.

Bruce

[Kenneth Hertzog]

Scott
I've put a diamond drag in my CNC machine and did not run the motor
this put a very nice engraving on the brass.
got the fixture from 2linc dot com
ken

[Scott Shepherd]

Thanks, I can't take the nose cose off, it's what controls the depth of the cut, and they want it to be engraved and paint filled. It needs to be seen from 6' away or so, so diamond dragging isn't an option.

[Robert Walters]

Steve,

I'm not familiar with the machine (though watched a couple of videos) but when Z retracts to move to the next letter, is there enough clearance to allow the vacuum to suck up chips before coming back down?

Is there any blockage in the vacuum that would reduce it's effectiveness?

Have you considered using a small shopvac while it's engraving and see if that helps any?

I watched the LOOOONG (auto play) video here of them doing aluminum and various brass: http://www.xenetech.com/support-vide...Rotary-Samples, and I didn't see any such thing as you mentioned.

[Scott Shepherd]

You can adjust the clearance for moving around, but the vacuum isn't strong enough to pull metal chips through it too well. I suppose I could sit there with an air hose and blow the chips off, but I'm sure there's a technique used as many people do this.

In the video, starting around 4:30 and moving forward, they have the nose cone with the vacuum attached.

The way it all works is you set the cutter depth (how far it sticks out past the nose cone) and then when it the nose cone hits the work, it won't go any deeper. So the nose cone riding on the work is what controls the depth. So if the cutter kicks up a burr on the edge while cutting, then the nose cone will ride up on the burr and make the depth shallow.

[David Epperson]

I've avoided engraving polished brass for years because I could never figure it out. What always happens to me is that the brass chips from cutting get caught under the nose cone when the Z lifts up and moves to the next feature. Then it drags that chip all around the nice polished finish and ruins it.

I removed the vacuum nose cone and replaced with with a leaner, meaner nose cone and thought it would work better. I put transfer tape on the surface that will be engraved to protect it, but what happens is as it's cutting, it's moving tape around, like around the letter "N" and such. So now that it's lifting that transfer tape, the nose cone senses that bunched up tape and cuts shallower. So my effort to protect the work ends up causing the depth to get all messed up.

We have the old Hermes Pantograph and I hate to drag that thing out, but I'm getting close to it. At least there, you can control all the things that would cause a scratch.

Any tips or pointers on how to engrave polished brass on a machine that uses pressure on the nose cone?

Thanks in advance-
Steve

Take this for what it's worth from someone who knows very little about the actual process (my signature line applies here)- but could you replace the "tape" with some other "removable" protective film - like shellac? Mask and "paint", engrave, then wash the shellac off with alcohol.

[Wil Lambert]

How about adding a small air line that is attached to the head for a constant air blast. Use a small diameter hose on it. Depending on the air flow need maybe a fish tank air pump on it. Tubing is small and they are rated for continuous duty.

[Robert Walters]

You can adjust the clearance for moving around, but the vacuum isn't strong enough to pull metal chips through it too well. I suppose I could sit there with an air hose and blow the chips off, but I'm sure there's a technique used as many people do this.

In the video, starting around 4:30 and moving forward, they have the nose cone with the vacuum attached.

The way it all works is you set the cutter depth (how far it sticks out past the nose cone) and then when it the nose cone hits the work, it won't go any deeper. So the nose cone riding on the work is what controls the depth. So if the cutter kicks up a burr on the edge while cutting, then the nose cone will ride up on the burr and make the depth shallow.

1) I wouldn't BLOW the chips away as much as suck them up, no need to get them stuck in the mechanics.
That's why I suggested using a small shopvac.

2) Also in the video they have the nose cone completely removed.

Sure, it may have a "depth gauge" built in, but if you are engraving flat surfaces, once the initial height is set, you don't need to readjust that unless you change materials.

[Scott Shepherd]

Robert, it doesn't work like that. The depth is 100% controlled by the nose cone and how far past that it sticks out. You cannot remove it and rotary engrave. When you see if on the video with the nose cone off, it's because they are using spring loaded attachments like the burnisher or the diamond drag, where there is no depth needed, only pressure. However, when cutting, you have to have the nose cone on to control the depth, unless I'm missing something.

[Rodne Gold]

If you want to engrave without as nose cone with a "solid" (IE not spring loaded) Z , you need to make a sacrificial table out of acrylic or whatever , stick it on the bed of the machine and mill it with the enagraver to be flat ...this will enable very precise depth control. Im sure your machine has a way of making the Z solid.
If you use engravers brass and tungsten carbide bits , you can engrave dry , other brass will require parafin or other lubricants like shell dromus or Diatsol to engrave well.

[Mike Null]

Steve

I believe you can remove the nose cone and regulate the depth with the micrometer on the spindle. Be sure your vacuum is working well. Sometimes the vac is attached to the nose cone so you may have to hold it by hand or devise some other means of attaching it to the spindle.

You may have to make several light passes and it is critical that your table and cutter be in the same plane. (equate it to focusing the laser)

I generally use the diamond drag for brass.

[Ross Moshinsky]

We do a ton of gold brass every year. What software are you using for engraving? There should be some setting which allows you to change your "hovering" Z. What I mean is, on my machine, I can change the Z to lift up a set amount between letters. I have it lift up about 1/8". Since the bit is not near the material as it changes letters, it can't scratch.

As for bits, we you rotating burnisher bits or diamond rotating burnisher bits. JDS sells them and they are relatively good. To get enough depth for paint filling, another bit may be required though as neither of the bits I'm suggesting are really meant to go much deeper than .01"

[Scott Shepherd]

I found it. You cannot do with with the micrometer adjustment, as mentioned before, that all works together and you can't just remove the nose cone. It will drive the cutter through the work piece into the table if you do.

I found the instructions on their site for doing it. You have to disable the pressure sensing adjustment in the software, send the job over and manually do some stuff to bring it to a place to engrave. The bad part is that the instructions use terminology that's not listed anywhere in the rest of the manual, so it tells to you move things and there's no idea what it's talking about.

I'll just do it on the CNC router and call it a day. Shouldn't have to and don't want to, but I also don't want to spend 8 hours trying to figure this out.

[Robert Walters]

I found it. You cannot do with with the micrometer adjustment, as mentioned before, that all works together and you can't just remove the nose cone. It will drive the cutter through the work piece into the table if you do.

I found the instructions on their site for doing it. You have to disable the pressure sensing adjustment in the software, send the job over and manually do some stuff to bring it to a place to engrave. The bad part is that the instructions use terminology that's not listed anywhere in the rest of the manual, so it tells to you move things and there's no idea what it's talking about.

I'll just do it on the CNC router and call it a day. Shouldn't have to and don't want to, but I also don't want to spend 8 hours trying to figure this out.

Wait, what?!

You have a CNC router, does it have a automatic depth gauge (probe)?

It seems you found the section for your engraver that allows you to set Z height manually.

Basically set the Z tool height to the top of the (flat) material, in this case the polished brass.

Once the tool is almost touching the top of the material, zero out your Z axis.

At least that how I do it on my CNC router. I'd guess your engraver has similar functionality/capability.

If all else fails, I'll give ya $100 for it