Author Topic: Dah Lih DL-VHR-GIF mill - a journey of discovery  (Read 2526 times)

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #15 on: November 13, 2018, 09:10:48 AM »
Some more fettling and improvements.

I was finding the Z axis really stiff on going up and when letting it down it would "judder".  I had thought i had too much slop and it was locking on the way down.  Actually it is much simpler than that, the gib screws were too tight.  It was the first time I had looked at them.  After a little tweaking the Z axis is nice and smooth.

Next challenge was Y axis. Quite a bit of excessive slop here, about a 1/4 turn of the wheel and when milling with heavy cuts I could feel the give when the end mill grabbed and moved the table a little.  Definitely not ideal.  So I went hunting for the adjustment (oh please let there be adjustment).  And I found this arrangement:


Now this image is post adjustment. Imagine this with only the top M6 screw and with no clamping washer. So first off another M6 screw and two custom clamping washers whipped up on the lathe.  Then some tweaking by backing this nut off then re-clamping the M6 screws to drive a little loading on to the leadscrew.  Net effect is a really smooth wheel action and a backlash of 0.04mm.  I think I can live with that.  :whoohoo:

Cheers,
J.
James
Wellington - NZ

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #16 on: November 19, 2018, 08:31:16 AM »
Okay I'm getting lazy in my old age and doing these videos shows way more than a set of static pictures.

What we have here is ...

[1] Video showing the new chinese sourced digital tachometer in operation against the high gear.  If anyones interested I can take some photo's of how I have the sensor and magnet setup in the head.

[2] showing the tapping speeds and the speed of stopping and reversing when under VFD control.  I've used this setup to power tap M10 into 6mm steel with no worries at all.  I suspect it will do a lot thicker and at some point I'll dig out some 12mm scrap and try it on that.

Cheers,
James.
James
Wellington - NZ

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #17 on: November 21, 2018, 07:05:09 AM »
The learning continues both in how to set up the VFD but also in how to use the mill.   I setup on Gear 2 which had a name plate top RPM of 700.  It was actually spinning out about 800 rpm.   For drilling with a 6mm pilot hole and then to dialling it back a little for the M10 tapping drill size. Then pulling things back to the low gear belt and running at 25% of max frequency (15Hz) for the tapping.  Which gave about 140 rpm.  Once I have everything setup with the final parts I should be able to get down to between 5-7 Hz, so about 60-70rpm.

The key learning with the current setup I have which is 8 preset speeds from 100% down to 12.5% is that I can have custom ramp up and ramp down rates.  So for the two bottom settings I have it decelerating at 60Hz/sec.  This means the spindle stops FAST, or for that matter moves from forward to reverse pretty dang fast as well.  Where as for the higher speeds I have a more leisurely 30Hz/sec rate which just keeps things less stressed on the motor.  It still stops in ~2 secs.

Have a look at the video of power taping for M10 x 1.5 into 16mm steel.  Pretty cool and quite fast.
James
Wellington - NZ

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #18 on: November 25, 2018, 07:24:53 AM »
In the process of building a tailstock support for a rotary table i got to power tap M10 x 1.5 holes through 30mm of mild steel.  This 1HP motor on low gear (not a back gear) under VFD control just munched trhough it at about 80-100 rpm.Not single sign/sound of strain.   :whoohoo:

James
Wellington - NZ

Offline Admiral_dk

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #19 on: November 25, 2018, 09:39:44 PM »
Sounds like you got yourself a very nice mill after the mods  :ThumbsUp: congratulations  :cheers:

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #20 on: November 27, 2018, 08:14:39 AM »
I thought I would post some pics showing how I had setup the digital tacho on the mill. It's not particularly special I guess but just in case someone finds it useful.  It seems to be working well and in the end allowed me to mount all the parts without having to glue anything to something that would require destructive removal when wanting to get back into the spindle assembly.

Overall view looking down into the belt housing.  You can see the collar that I made from aluminium to hold the magnet.  The hall effect sensor and the bracket its on. On the collar you can see the M4 screw used to clamp the collar onto the top nut on pulleys.


Just turned around to show the magnet.  Press fit into the collar.  I don't think its going anywhere.  :-)


Looking at the side of the housing and you can see the bracket clamped on to the side grill.
« Last Edit: November 27, 2018, 08:27:52 AM by Joco »
James
Wellington - NZ

Offline bwal

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #21 on: December 14, 2018, 10:32:01 PM »
HI Jo,

Where did you get the parts for the digital tacho? Ebay? That's something I'm interesting in doing on my mill.

Ben.

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #22 on: December 15, 2018, 01:50:44 AM »
Ben - got them off AliExpress.  But I suspect the same thing is available on eBay.
James
Wellington - NZ

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #23 on: December 16, 2018, 07:51:22 AM »
Some progress today on finally getting the new buttons and speed potentiometer (POT) working.  I had been having issues with the external POT not being recognised on powerup.  It all came down to having to use shielded cable.  I was using Cat5 UTP and while this worked fine for the buttons the POT was being problimatic.  I did a test with some 3 core shielded cable and it started working correct from startup. So since I had to have about 6 wires for to one of two VFDs I shifted to Cat 6 STP (actually SFTP) and we have a nice tidy run, fully shielded and working correctly.


The buttons are
Top row from left: Stop, Forward, Reverse, Speed Dial
Bottom row from left: Table feed On/Off toggle, Pump on/off toggle, eStop that kills table and spindle. Once I get the CNC BF20 built I'll engrave the lables on this plate.




The POT is an interesting on I got from Banggood.  Its a 10k ohm multiturn POT with a neat dial that shows the turns and the graduation in a turn.  Want to get to about 50% speed, turn to the outer number is 5.  Then adjust from there to get the rpm that works best.




So after this success and while I happen to have the vice off I decided to do a more accurate tramming of the head from left/right to the table.  I had done this previously on the vice and had to pretty good but felt it could be done better.  So I setup my 0.01mm DTI to trace an approx 430mm diameter circle. Given that size circle this should provide some pretty good sensitivity. So after a few sweeps and some nudging on the spanner we got ourselves to this position:

 

I think over 430mm we can call this good.  To do any better I'm going to need a 0.002mm DTI.

Cheers,
J.
James
Wellington - NZ

Offline Admiral_dk

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #24 on: December 16, 2018, 06:38:32 PM »
Great accuracy - you should be very pleased  :cheers:

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #25 on: December 23, 2018, 07:58:48 AM »
A little more progress today.  The plan to be able to run the horiztonal and vertical spindles off the same VFD is starting to come together with the arrival of this big ass changeover switch.

The two motors are VERY similar with all the VFD parameters being the same plus the change over wont be done without powering off the VFD. Given that moving to horizontal milling is quite an exercise this depowering process shouldn't be an issue.


So taking the eletronics box door off and mounting on the table so as to thin the 6mm aluminum down a little, in the same way as the existing power switch has been seated. Used a HSS 12mm 4-flute end mill running at 1700 rpm.  A bit of WD40 and a robuts feed rate and things were cutting very nicely with nice tight chips.




The resulting switch mounted and the door back in place.  The intention is the left-hand switch will be Master Power and the right hand swicth will be Spindle Drive Selection.  Once I have things a bit more sorted I'll be taking the old signage off and replacing with something else. Ideally carved on a yet to be completed CNC'd BF20.


Cheers,
J.
James
Wellington - NZ

Online Muzzer

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #26 on: December 24, 2018, 05:53:44 PM »
Hi Joco

Looks very nice! Handy having the horizontal spindle too, particularly as uses the same tooling.

BTW, from my own investigations, it seems that BT30 is only ever used with pull studs, whereas NMTB30 (imperial) / ISO30 (metric) have the extension collar for a drawbar. However, it doesn't really matter which you use on a manual mill if you have a different drawbar length for each - slightly longer for the BT30. On my ISO30 Bridgeport clone I use both. I actually have a pullstud system and simply use longer pullstuds for the BT30 tooling, which is more readily available.

The backlash arrangement that uses 2 nuts may not be the end of the story. If there is any noticeable wear on the leadscrew, it will be worse in the "middle" of travel where it has seen most use. If you minimise backlash there, you will find the leadscrew becomes very tight as you move the table away from that position. This will force the nuts apart and possibly distort or strip the adjustment screws. There's no simple solution apart from tightening the table locks and/or using a DRO to compensate. I've fitted Chinese rolled ballnuts to my X and Y axis and that has reduced the backlash to something like 0.01 - 0.02mm or so.

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #27 on: December 25, 2018, 07:25:22 AM »
Cheers Muzzer.

Backash isnt looking too bad across the entire screw length.  But also have a DRO fitted which helps massively.

On the BT30, yeah have seen a lot of use of it in the CNC space with pull studs.  The confusing part is the horizontal arbor for the mill is also BT30.  So it “looks” like that is the intended taper as the horizontal arbor is orginal to the mill.  However I have a little spacer collar for the drawbar so I can use BT30 and NT30 with ease.  At the moment the draw bar on the BT30 seems to be working pretty well.
James
Wellington - NZ

Online Muzzer

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #28 on: December 25, 2018, 09:39:31 AM »
BT30 and ISO30 / NMTB30 are pretty much identical apart from the presence or absence of the collar (and a groove for an automatic toolchanger). It seems rather unlikely that your horizontal spindle was intended to take BT30, so if the drawbar is the right length for BT30, it suggests either it is longer than the original drawbar, or is missing a spacer. Does an NMTB30 tool fit too?

Sounds as if your wear is fairly limited - better than mine was!
« Last Edit: December 25, 2018, 09:43:01 AM by Muzzer »

Offline Joco

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Re: Dah Lih DL-VHR-GIF mill - a journey of discovery
« Reply #29 on: December 25, 2018, 06:33:51 PM »
Muzzer - NT30 and BT30 are the same taper as you noted and other than the “collar” look identical. I have a mix of a BT30 and NT30 holders and all fit nicely other than needing to use the spacer collar on the drawbar to account for the different lengths needed between BT30 and NT30.  For convenience I have been tending to get BT30 holders for new purchases. Just so I dont need add/remove the spacer on the drawbar too much.

My comment re the horizontal arbor is not to do with the drawbar length but that the actual taper on he horizontal arbor looks like BT30 as it is missing the extra collar length at the end of the NT30 holder.

Cheers,
J.
James
Wellington - NZ