Need to save my hearing - Spindle time

My PCB has this 6-pin location populated. Anyone know what make/model the mating connector part is?

there was a part number in another thread in the forum.
I do have the pinout (at least enough)

the right bottom pin is ground (brown in my cable)
the left middle is PWM (red in my cable)
(the top left is 24V)

this is from the angle of looking straight at the connector on the board with the board assembled on the Y rail, so from the front of the machine looking towards the back to the board

Please see:

that and other potentially useful links are at:

When describing the ISP header pins to the left of the board, I presume it is this connector:

EDIT: (almost) complete board map here:


AFIK you’d have to get something not made in China (i.e. not cheap) for that. But then, if you’re not cutting metals, 1/4" shanks should suffice. Personally, I’d go with the HSD. But, those that have purchased G-Penny spindles here seem to be happy with them.

btw… what kind of F&S do you use for a 1/2 inch cutter?
60ipm at 1mm DOC ? (e.g. similar to the #201 bit just wider)

That would be extremely conservative.

I run a 2.2kw spindle with an hdz. I am able to run a 2 flute 1/4” bit at 180ipm, 18k rpm, .250” doc and .125” step over.

I only use amana bits and thier feeds and speed charts are Great starting points. I’ve been eye balling a 1/2” bit. Amana lists 200ipm , 1/2” doc and 1/4” step over but I’m not sure if the belts can take it.

I only recently got a spindle (and it’s a bit smaller one) but yeah with HDZ I have been going at 170% of normal for some… but I will admit to being a bit conservative in F&S so far…

That’s an interesting question, and I don’t even own a 1/2" cutter yet so I could not say.
However if I just try and extrapolate my crowd-sourced rule of thumb chipload table,

I would guesstimate that for a 1/2" cutter in hard wood I would aim for 0.001" to 0.004" chipload as a starting point (and probably lean somewhat towards the lower end that range, since @gmack kind of convinced me that 0.001" is enough, and one should max out RPM and then just derive feedrate to be above that 0.001" chipload)

So a middle ground value would be 0.002", at 24000RPM that would mean ~100ipm for a 2-flute at 50% stepover, faster for lower stepovers. @quicky06 pulls off using 180ipm at 18k, so that’s a 0.005" chipload, there’s no question that depending on the material one can go higher that those values in the table.

For DOC, by default I would stick to my usual rule of thumb of starting with a max of 50%D, so 0.25" in this case, for non-adaptive toolpaths (and up to 300%D for adaptive at low WOC)

Most of the time I’m not optimizing for MRR anyway. I have this 8mm 2 flute I have been wanting to try to hog material, we’ll see if my little extrapolation here lives up to the reality, and I may need to buy a 1/2" cutter just for the fun of shredding material like there’s no tomorrow.

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For reference here is the amana feeds and sellers charts for straight end mills.

I use fusion so I have imported their tool list. And these are what the default tool settings are. I do some test cuts at 50% speed using a 1xD Doc and a 1/2 D step over. I work up to 100% with test cuts and having had an issue yet.

My biggest concerns is the belts on the machine. That chart lists but limitation (and conservative ones at that) not machine limitations.

I have been on the fence about buying a 1/2” bit ($$$) to reduce roughing times in Baltic birch. But I’m unsure of the belts can handle the load required. Especially for a 3 flute.

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Running a Trend 1/2" two flute

In a cheaper plywood (not as heavy as baltic birch) I ran Adaptive Clearing at:
5mm optimal engagement (WoC)
10mm stepdown (DoC)
And it was perfectly happy, I was even able to push the feed override up as it threw chips around the room.

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Thanks for the feedback, interesting, so that’s a 0.0015 chipload and 80%D for DOC in plywood.
Did you capture a video of your 1/2" cutter butchering the stock ? :slight_smile:

at that amount of violence I’ll start worrying about work holding :wink:

(sadly I only have an ER11 collet so limited to 3/8"… but I want to add a 1/2" bit to the tool library at in addition to a 3/8" and 5/16"… and figured that one I know what a 1/2" can do I’ll run the 3/8" at that same F&S)

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Not sure exactly what feed rates I grabbed phone video at, once I sped the feeds up I was a bit more focussed on the machine.

Here it is clearing out a side pocket in the ply, that’s a 204mm long side pocket it’s clearing out at 10mm depth and 5 engagement, seems like about 4.5 Seconds to cover 204mm based on the video

And yes, the dust extraction is running, it’s just the chips are being thrown straight past it.

Here’s the first go at a full pocket with Adaptive Clear, again. After watching it do the first pocket like this I hit the feed override to see how much faster it would go. The big cutter clears chips out of pockets with no problem and didn’t tear up the surface even on this poor quality ply.

I suspect the large spinning mass of the cutter along with the rigidity back to the spindle of 1/2 inch of tool steel works as some kind of giant gyrostabilising wobble preventer.

This was quite a soft plywood, I’d be a lot more careful in a proper baltic birch.

Workholding wasn’t much of a problem as the cutter is straight flute so not pulling up on the workpiece. When I used the cutter to do some joinery on a 2x4 however, the workholding was definitely on the “step away from the machine” side of happy. Not sure what feed rate this is but I’m getting chips not dust :wink:


Amana makes “Carbide Tipped Straight Plunge” bits for wood with 1/4" shanks and cutting diameters up to 1". So, you should be able to significantly increase your MRR by using more of your spindle power without increasing cutting forces. But, beware that the glue in light weight Baltic Birch will chew up HSS cutters. It will also likely require more cutting power.



it’s unlikely that I will use baltic birch for finegrained high detail 3D carving :wink:

price was quite reasonable so it’ll arrive in a few days :slight_smile:

thanks for the heads up @gmack

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I have a 1” with a 1/4” shank.

They do not plunge well. With an hdz it’s not an issue. But a belt drive z will loose steps undoes you ramp slowly.

I actually stopped using them to rough out material because I can run a 1/“4 bit sooo much faster that it doesn’t really save me any time especially when I have to do a bit change to get into smaller areas.

What speeds do you use?