Static control for shop vac?

@falviani Welcome back, Frank.

I have spent far too much time playing with grounding solutions for my dust collection set up. To ground the hose on a vac will be a bit more of a chore, assuming you want to be able to remove the hose from the vac easily. My set up is for a dust collector, using a combination of rigid PVC and flex hose. I’ll let others using a vac chime in, likely with better ideas than mine.

Speaking generally of freezes, what you are running for your gcode sender? If you are using UGS, make sure that you are running the December 2020 2.07 version.

Yeah, UGS. I’ll check the version. Thanks for the info.
I was planning to wrap light copper wire around the hose, securing it periodically with duct tape, and connecting it to a hacked modular power cable (1 tab removed) that can be plugged into a standard 3prong extension cord.

@falviani That’s a good approach, Frank. I did the same for my set up. In fact, I have a wire inside the duct and I’m using aluminum duct tape on the outside. Like you, I removed the prongs from a 3-prong plug, leaving only the ground prong, and I have copper wire running from the tape and the inside wire to the plug on my power bar. Some days, it actually works. :expressionless:

My guess and it is only that, is the sender or feed rates. I read a lot about issues with UGS lately so there must be some issue there. Touch wood but I haven’t had issues with UGS but I am running the October 2019 version which is what I installed when I received the machine. However, I have had issues when I push the feed rates above 155 inches a minute. When doing 3D carves I keep the rapid travel on the X axis. I can run a 1/4 TBN all day long at 155 IPM but if I push the machine to 180 IPM it will occasionally miss steps. I suspect a few things contribute to this. First the sheer load on the router could be stalling the motor and/or the processor can’t keep up with the combined X and Z gcode. I have never (touch wood) had an issue with static charge.

@JRich63 Welcome back, Jeff.

“I have never (touch wood) had an issue with static charge.” I could learn to hate you. :grinning: :grinning: :grinning:

What do you use for dust collection?

In terms of feed, keep in mind that the Mill is limited by grbl setting to 4000mm/min (158 IPM) in X and Y and 3000mm/min (118 IPM). So, it doesn’t matter what we set our CAD/CAM software or our gcode sender to, the Mill will not go faster than that. It’s interesting that your experience says that if you set the feed to 180 IPM, you lose steps. I wonder if the conflict between the grbl settings and the UGS settings is causing that.

I use a Rigid vac with a cyclone. On my machine the Y axis is set to 4,000 as you noted but my X is set to 5,000 or 200 IPM. So it will do 180 on the X as I noted.

@JRich63 Sorry, Jeff, I didn’t take in to account that you could, and did, go into grbl and change the speed parameter. At some point, the guys wrote about the Mill losing steps when the speed was set higher.That’s likely what you are experiencing, FWIW.

I have one of the first machines off the line and that was the factory setting at the time. They did suggest changing it but I never did. My philosophy is if it ain’t broke don’t fix it. Lol

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I went and tried to add static control to my shop vac. I wound light gauge copper wire around the outside of the hose (held in place at roughly 1 ft intervals with duct tape), connected to a hacked modular cord - connected directly to the green ground wire and 1 prong removed so no power could flow. DIDN’T WORK. :rage:
It was running for about 10 minutes when it stopped for a few seconds, ruining the carving. I decided to see if the outline toolpath was OK, and that only went about 2 passes before the downcut 1/4" endmill jammed.
I’m wondering if the bits have become unusably dull. I have a (not too good picture) of the ball nose and down cut mills here:
The downcut shows slight traces of blue, as if it overheated, and what might be dulling; the ball nose has a slight glint along the cutting edge, as if it was getting rounded over.
While it would be noticeably more costly, should I consider switching from MDF to poplar?
Also, any favorites among tools? I’m retired, so I’m not interested in spending big bucks for tools aimed at production shops.
Any thoughts would be appreciated.

@falviani The pics seem to show that the bits have blued from reasonably serious overheating. Are the edges of the MDF burnt? What are your feeds and speeds in MDF, Frank?

I cut quite a bit of MDF, but use mostly 1/8" bits to get the detail that I need.

In terms of bit sources, I get most of mine from Sienci. Their quality and prices are good, I find. You can get cheaper from China on Alibaba or Amazon. I can’t vouch for the quality.

I think the blue cast is from the photo - they’re not that blue in the shop lighting (LED flourescents). There’s no hint of burning in the MDF.
The endmills are from Amazon.
1/4" ball nose - 70ipm
1/4" downcut - 50ipm
I generally keep the router at about 4, which is roughly 20K rpm.
I’ll look into the Sienci bits - I"ve bought several from them before.

I think, for that router speed, you are feeding much, much to slowly. You will be burning your bits. The problem is that, if we want to use 1/4" bits, the Mill will not move fast enough, even at the slowest speed on a Makita router, to hit any of the chip load charts. I believe that, running at the that feed rate and at that speed, you will dull bits very quickly owing to heat, especially in MDF.

Wow where is the old Grant? And what did you do to him? :stuck_out_tongue_winking_eye:
Can remember he was saying

Think we got you to the right side of light :smiley: :blush:

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@JHahn I’m not quite on the side of light, yet, Jannik. :grinning: For 1/4" bits, I have not found a chart yet that I can comply with. Between the speed limitations of the Makita router and the limits on the Mill, I believe it’s impossible to hit the mark. Since I do mostly MDF stuff, I still listen to the bit and change feeds and speeds on the fly.

When using 1/8" bits, I’ve now found one chart that I can meet. On plywood and cherry, its numbers seem to give me good chips and no burn. However, I still rely mostly on how things sound during the cut, then I make a note of that so that I can repeat it next time. So, I guess you could say that I’m still not quite willing to accept all the “science”. :grinning: I do accept that it can give us a good jumping off point, though.

In this thread, though, the pics that Frank posted seemed to show serious burning of his bits. He has since clarified that it’s just lighting. Since he asked if the bits were dull, and the pics seemed to show that they likely were, I threw out the idea of feeds and speeds.

@falviani To Frank: One thing that I did not mention, but that you likely already know is that MDF and plywood are really though on bits. All the glue and binder in them wears even carbide down very quickly. On V bits, I use a diamond hone to keep the edge as keen as possible. I’ve not found a way to do that on end mills.

I was just kidding Grant, I am completely with you. 70 ipm is painfully slow for a 2-flute 1/4" bit.
Its better to reduce to load by lowering the depth of cut or step over and not the speed.

Sorry for beeing offtopic again, but I think what you do with your ears and a pencil actually is some science. Not the same science like this but kind of :wink:

@JHahn I knew that you were kidding, Jannik. Lately, I have been considering chip load more than I did months ago. The chip load calculator put out by US router tools seems to be a good starting point. There is a youtube channel - cuttinitclose - that is really interesting. He talks about chip load, but also goes into the limitations of hobby machines and how those limitations affect feeds and speeds.

That video you linked to is incredible. I still find it somewhat counter-intuitive that taking a bigger “chunk” can be better for the machine. Still much to learn.

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Interesting. The F&S table Sienci has up suggests feeds much slower than I’m using - around 55 IPM. I’m going to try switching to poplar, new bits, and higher speeds (100 IPM for the ball nose) to see what the results are.
Do you have 1 or 2 references to F&S tables that you’d consider reliable and usable? I don’t want to spend the money on the calculator from CNCCookBook, being retired.
Thanks in advance!

@falviani @JHahn I’m with you, Frank. I would never pay for one. Here is a link to the one that I am playing with. Jannik has me all wrong, though. :grinning: This is not a bible to me. It is serving as a stepping off point, though.

Looks useful, but the numbers it calculates seem very high to me. I need to watch that cuttinitclose Youtube video for more info.

@falviani That’s interesting, Frank. Don’t get me wrong, I’m not arguing with your take on those numbers. However, I find myself increasing those numbers on the fly when I run jobs, based on how things seem to be cutting and the sound that it is making.

Some time ago, I think that there was a thread on here, the idea of which was going to be an exchange of experiences with feeds and speeds. I guess that it didn’t get off the ground.