Boxford changes

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Steve Rodway

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Jul 5, 2021, 10:46:30 AMJul 5
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Hi All,
I've made a few changes to the boxford CNC mill's setup that users
should know about

A) Increased homing speed
The machine now homes at approximately twice the speed it used to,
don't be surprised when it moves faster than normal!

B) Spindle respects E-stop correctly
The spindle motor now properly respects the E-stop button and will not
auto-restart when the E-stop is released. When you want to recover from
E-stop you just need to release the button and use the "unlock" function
like before, no need to send an M5 before you unlock

C) Increased Rapids
I've increased the maximum permitted travel speed to 1000mm/sec so that
jobs can be run faster, and may increase it further in future. So far it
appears to be working well at the increased speed but speeds over
800mm/sec at entirely at your own risk! If you do use them and it either
works or doesn't work please let me know so I can use the information to
optimize the settings.

Inductions continue to be available for this tool and I'll run sessions
whenever there's enough people on the waiting list

Steve

Andy C

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Jul 6, 2021, 9:20:10 AMJul 6
to rLab / Reading's Hackspace
I am having a lot of fun and learning a lot on the Boxford. If you're interested in metalwork/engineering, I highly recommend it. Watch out though, the learning curve is a little steep, my record so far is 4 broken tools in one session.

If you're interested, you can see some photos and a couple of videos of my projects here, including this time-lapse of my disastrous session.

I've also started trying to keep a log of my tool usage and success/failure here. Maybe that will be useful to others. I'd welcome collaboration if anyone wants to contribute.

Some other notes/learnings:
  1. I seem to have to use the rubber mallet more and more to extract the chuck from the machine. Particularly after a few operations.
  2. The 4 - 3 collet is really tight with 4mm tools. It was a struggle today - grips were needed. I imagine we're using 3.175mm tools quite a bit, could this have 'shrunk' the collet?
  3. I've had the compressor overheat in two sessions now. That causes a bit of panic once you notice the chip build-up. Today I set up the shop fan to blow onto it. I don't know if it made a difference, but it didn't happen again.
Anyway, thank you to Steve for getting the machine running, the maintenance of it and the advice and training for using it!
Andy

Alex Gibson

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Jul 6, 2021, 10:36:50 AMJul 6
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So did you work out what was actually causing the tool breakages?

 

Cheers,

 

Alex Gibson

 

+44 7813 810 765    @alexgibson3d    37 Royal Avenue, Reading RG31 4UR

 

admg consulting

 

edumaker limited

 

·         Project management

·         Operations & Process improvement

·         3D Printing

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Steve Rodway

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Jul 6, 2021, 11:40:34 AMJul 6
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Things I'd mention

Carbide is not really a good choice for small tools on the boxford,
although it's generally a superior material, it does demand higher
cutting speeds than the boxford is capable of to get the best results,
HSS or 8% Cobalt tools may work better here. Shop-APT provides 8% cobalt
tools down to 1mm diameter although they are little more expensive than
the usual eBay/Amazon suppliers

Slotting like that is one of the hardest operations to do, you might get
better results by modelling the slot as wider than the tool (if that's
practical for your job?) then using a 2D pocket clearance toolpath with
multiple depths specified. That'll result in it only trying to cut very
shallow slots with a little space around them to allow for better chip
clearance.

On point-1, yes I'm seeing the same, I'm reluctant to invest too much
time in fault-finding there though as we might wind up re-building the
spindle soon.

Point-2, OK I'll order a spare, they're not expensive

Point-3, Yes that's an issue I've had too. It's worth noting that even
small drops in the air-blast pressure will result in substantially
reduced load on the compressor so if you're able to reduce that even a
little it's likely to resolve the issue. Can also help to turn the
downstairs air-con on high while you're working and make sure the
compressor is in range of it. We're considering a compressor upgrade at
some point that should remove this issue entirely.

Steve

On 06/07/2021 14:20, Andy C wrote:
> I am having a lot of fun and learning a lot on the Boxford. If you're
> interested in metalwork/engineering, I highly recommend it. Watch out
> though, the learning curve is a little steep, my record so far is 4
> broken tools in one session.
>
> If you're interested, you can see some photos and a couple of videos of
> my projects here <https://photos.app.goo.gl/3HsSzYLaDcThvJJRA>,
> including this time-lapse
> <https://photos.google.com/share/AF1QipMv88JHPpHQBpFAmCuEqAbj8uWa6QZ8UhWvx2owxDzY9ixMxzAdyva47ZhdPLDLaA/photo/AF1QipNY1PGR5fbNBtkvhrrg5xb-9CqqrxlJLa4PrH4C?key=X2dSOGFybUxIaXVZczVJTEZMd0xiYmFZNzJseGpn>
> of my disastrous session.
>
> I've also started trying to keep a log of my tool usage and
> success/failure here
> <https://docs.google.com/document/d/1oleGbisOdjidyUlOG0hp37Jn8Jut1l1At75jPGPmVLQ/edit?usp=sharing>.
> Maybe that will be useful to others. I'd welcome collaboration if anyone
> wants to contribute.
>
> Some other notes/learnings:
>
> 1. I seem to have to use the rubber mallet more and more to extract the
> chuck from the machine. Particularly after a few operations.
> 2. The 4 - 3 collet is *really *tight with 4mm tools. It was a struggle
> today - grips were needed. I imagine we're using 3.175mm tools quite
> a bit, could this have 'shrunk' the collet?
> 3. I've had the compressor overheat in two sessions now. That causes a
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Steve Rodway

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Jul 6, 2021, 11:45:39 AMJul 6
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Looking at the settings that Andy is using, I'd say in each case of
breakage, the feed rate is substantially too high. Annoyingly the
boxford simply isn't very well suited to using very small tools because
the spindle is too slow. That's also something I plan to look at
changing but it probably won't happen in the immediate future.

Steve

On 06/07/2021 15:36, Alex Gibson wrote:
> So did you work out what was actually causing the tool breakages?
>
> Cheers,
>
> Alex Gibson
>
> +44 7813 810 765 @alexgibson3d 37Royal Avenue, Reading RG31 4UR
>
> admgconsulting
>
> edumaker limited
>
> ·Project management
>
> ·Operations & Process improvement
>
> ·3D Printing
>
> *From:*reading-...@googlegroups.com
> [mailto:reading-...@googlegroups.com] *On Behalf Of *Andy C
> *Sent:* 06 July 2021 14:20
> *To:* rLab / Reading's Hackspace
> *Subject:* [RDG-Hack] Re: Boxford changes
>
> I am having a lot of fun and learning a lot on the Boxford. If you're
> interested in metalwork/engineering, I highly recommend it. Watch out
> though, the learning curve is a little steep, my record so far is 4
> broken tools in one session.
>
> If you're interested, you can see some photos and a couple of videos of
> of my disastrous session.
>
> I've also started trying to keep a log of my tool usage and
> success/failure here
> <https://docs.google.com/document/d/1oleGbisOdjidyUlOG0hp37Jn8Jut1l1At75jPGPmVLQ/edit?usp=sharing>.
> Maybe that will be useful to others. I'd welcome collaboration if anyone
> wants to contribute.
>
> Some other notes/learnings:
>
> 1. I seem to have to use the rubber mallet more and more to extract the
> chuck from the machine. Particularly after a few operations.
> 2. The 4 - 3 collet is *really *tight with 4mm tools. It was a struggle
> today - grips were needed. I imagine we're using 3.175mm tools quite
> a bit, could this have 'shrunk' the collet?
> 3. I've had the compressor overheat in two sessions now. That causes a
> <mailto:reading-hacksp...@googlegroups.com>.
> <https://groups.google.com/d/msgid/reading-hackspace/4f5d1cc0-7d5c-433f-a18d-a0505c1019e7n%40googlegroups.com?utm_medium=email&utm_source=footer>.
>
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>
>
> Virus-free. www.avg.com
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Andy C

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Jul 6, 2021, 1:07:39 PMJul 6
to rLab / Reading's Hackspace
> So did you work out what was actually causing the tool breakages?
>  in each case of breakage, the feed rate is substantially too high
Yup, or too deep. Or too many flutes. Or some combination of all three. Today I managed a couple of 2mm slots at 1mm deep at 150mm/min using a single flute tool. It also had shorter flutes than previous attempts (4mm vs 6mm). I'm trying to find a balance between an 80-minute cut that saves the tool but overheats the compressor/spindle and a 30-minute (planned) cut that snaps the tool.

I've been reading about issues with chip welding when using TiAIN coatings in aluminium, so have been staying away from them. This reduces the shop-apt choice quite a bit. Have you tried TiAIN in alu?

> Slotting like that is one of the hardest operations to do
Yes, I've been learning about it. Slotting is a bugger. I'm minimising it now, but some of my designs really want a slot.

Nice tip about the air-con and pressures. I'll try that next time.

Andy


Steve Rodway

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Jul 6, 2021, 1:16:16 PMJul 6
to reading-...@googlegroups.com


On 06/07/2021 18:07, Andy C wrote:
> > So did you work out what was actually causing the tool breakages?
> > in each case of breakage, the feed rate is substantially too high
> Yup, or too deep. Or too many flutes. Or some combination of all three.
> Today I managed a couple of 2mm slots at 1mm deep at 150mm/min using a
> single flute tool. It also had shorter flutes than previous attempts
> (4mm vs 6mm). I'm trying to find a balance between an 80-minute cut that
> saves the tool but overheats the compressor/spindle and a 30-minute
> (planned) cut that snaps the tool.
Yeah, it's an annoying compromise, although there's sometimes tricks
you can do with splitting a long path into multiple smaller paths either
by selecting only some of the geometry to mill on each one, or using the
top and bottom height controls to split the path into vertical bands.

>
> I've been reading about issues with chip welding when using TiAIN
> coatings in aluminium, so have been staying away from them. This reduces
> the shop-apt choice quite a bit. Have you tried TiAIN in alu?
It seems to go OK on larger tools where you can meet the speed
requirement at 3Krpm, but for smaller stuff I've had a lot of
chip-welding issues. I'm preferring uncoated carbide or HSS for smaller
tools.

Steve

Alex Gibson

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Jul 6, 2021, 1:24:42 PMJul 6
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Thanks - understanding the issues you had is tipping me away from trying my luck with milling a heatsink - especially that things will get exponentially harder to keep within breaking point of smaller diameter tools through a combination of factors.

I've changed some prototype designs I have to instead incorporate an off-the-shelf extruded heatsink with a custom heat spreader that I mill...

Cheers,

Alex Gibson

+44 7813 810 765 @alexgibson3d 37 Royal Avenue, Reading RG31 4UR

admg consulting

edumaker limited

• Project management
• Operations & Process improvement
• 3D Printing


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Mr E

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Jul 6, 2021, 1:24:54 PMJul 6
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One thought - what about doing the first "circuit" with a fairly light depth of cut.  Then stop, and literally fill that channel with cutting oil/gunk?  I think we've got something we use on the lathe.  That way as it finishes the job, it will be in a "bath" of oil.  Then have the air blast more cooling the top half or turn it down a lot, so it doesn't blow all the oil out of the groove. 

Small slots are the worst, as it's a tiny tool and the first hint of chip welding and snapped!  Too much heat into the cutter, then the metal will stick and next half revolution ping - and you just broke another.  Oddly going too slow can be a thing as well, so I guess experiment in both directions.

Rupert

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hugh griffiths

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Jul 14, 2021, 12:37:18 PMJul 14
to rLab / Reading's Hackspace
Andy, 
Love the time lapse video and will do one on my next job!
The end results look great and I feel your pain seeing those tiny cutters snapping like carrots! (as toolmakers used to say..)
Only had one incident with my job, where the 10mm cutter doing the outer profile was feeding too aggressively, ploughed in and shifted my job sideways on the bed.. The fact that the job shifted allowed the tool to survive and the job was recovered, so I got lucky!
Only 1 pic of my job (footrest holder for a motorbike) and I attach the Fusion file here if anyone wants to look at toolpaths, settings etc.
And again, many thanks to Steve for the induction and all the help.
Hugh
IMG-20210702-WA0009.jpg
FootrestLH03 v9 final v1.f3d

dave....@googlemail.com

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Jul 14, 2021, 7:31:34 PMJul 14
to rLab / Reading's Hackspace
I instantly thought of this thread when I saw the tool breaking post

Very impressive. I own a 3018 engraver and managed to cut 12mm plywood cogs, I'm sure my experience was
Similar to the experience with steel, however my tool chain might be a lot crankier (pardon the pun).

(Gearbox still didn't work as the flanges used grub screws that slipped, and coach bolts were 7mm not in fact 8mm).
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