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Thread: Boring out an impeller collar
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6th May 2018, 09:14 AM #16.
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Bob,
There is a good chance that impeller would fit on the stumpy 13's table. You are more than welcome to bring it around and we could have a crack at boring out the hole.
Bob.
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6th May 2018, 09:29 AM #17Member: Blue and white apron brigade
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10th May 2018, 10:36 PM #18Member: Blue and white apron brigade
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Spent the whole day with Anorak Bob, got a tour of his workshop and his drawers (cupboards) where there are some rare and interesting gizmos.
Most of the time we spent chewing the fat on MW gear, especially about Hercus Mills, but the real task of the day was to sort out a way of driving my dust collector (DC) impeller with a 24mm ID boss with a 4HP motor with a 28 mm shaft.
The initial plant was to bore out the 24 mm ID impeller boss to match the 28 mm motor shaft but that left no chance of returning the impeller to its original state if something went pear shaped so we went for Plan B which was i turn down the 28 mm motor shaft to 24 mm and add a new keyway.
I realize this is old hat to many folks on the forums but newbies may be interested.
Bobs Long Bed Hercus turns the shaft down from 28 to 24mm - looks swarf in the tray - her really does use his gear!
IMG_3017.jpg
Postioning the shaft centre to the centre of the milling cutter using a microscope attachment.
Rotor shaft leveling and perpendicularity relative to mill was performed using a dial gauge before clamping firmly
IMG_3018.jpg
Milling the slot.
It was a 7mm keyway and the closest cutter Bob had was a 1/4" So the cutter had to be moved (table is fixed on Mt Stumpy) and moved the bit 0.33 mm either side of centre over several passes to get the key to fit.
IMG_3020.jpg
CuttingKeyway2.jpg
After several whisker passes it fits! YAY!
Itfits.jpg
Done
I doubt it will make any difference but I will fill what remains of the old 8 mm keyway slot hole with a piece of steel to balance it all up.
Complete.jpg
Thank Bob - it was a pleasure watching a really careful craftsman at work and sovling the inevitable problems that arose.
Even though it was a relatively standard task I learned a lot.
Next I want to replace the motor bearings, reassemble motor ,and test the motor and impeller in my very rudimentary, temporary impeller housing and vibration test bed.
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10th May 2018, 11:28 PM #19Diamond Member
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You blokes didn't get stuck into the snake bight cure did you Bob(L)? I noticed that a couple of typos or straight out spelling errors have crept into your usual immaculate prose, just wondering.
Great job, BTW, and you do need to keep your fluids up in these dire economic times.
Rob.
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10th May 2018, 11:32 PM #20.
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It was a pleasure to spend the day working with you Bob and I'm glad our joint effort was a success.
Bob.
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10th May 2018, 11:34 PM #21Member: Blue and white apron brigade
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10th May 2018, 11:46 PM #22Most Valued Member
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Anorak bob, Did Hercuses come with a graduated tailstock as an option or did you make that?
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11th May 2018, 10:28 AM #23Member: Blue and white apron brigade
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Some proof of success will be in the comparative basic vibe test which I hope to run later to day after I pick up and install new bearings for the motor.
Testing in the dust collectors's impeller housing is a PITA because the Impeller housing and rest of the dust collector is inside an acoustically dampened enclosure located outside the shed and re/installing a motor in there is a right PITA. To get around the likelihood that I might have to install and reinstall the motor, I made up a sturdy closed wooden frame and box from 170 x 35 mm timber that can act as closed impeller housing and that I can clamp to a bench inside the shed.
The vibe test is very basic - I just run an iPad app called "Vibration" and put the iPad on top of the impeller and it records the X/Y/Z movements of the iPad. I will post some pics of this setup and some results later today. When running under he VFD I will measure the vibe as a function of frequency to see what it does.
As I said teh DC is outside the shed but the VFD and switches are going to be inside the shed. Because of this there's still quite a bit to do before I get the impeller running inside the DC including stripping out the old SP wiring which I foolishly installed under some internal Gyprock lining and I am hoping I can just pull it through the wall but I fear there may be 1 or 2 too many cable hold downs elsewhere down the to prevent that and I might have to take some gyprock lining off the walls. Then I will have to install a 3P cable and set up the VFD on a wall inside the shed. All good fun I suppose.
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11th May 2018, 11:06 AM #24.
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11th May 2018, 12:22 PM #25Most Valued Member
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11th May 2018, 09:27 PM #26Diamond Member
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Anymore info on the microscope attachment? Looks like a handy thing to have available.
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11th May 2018, 09:48 PM #27.
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Here you go Com - //metalworkforums.com/f65/t1771...97#post1701897
Probably the mill's most often used accessory.
Bob.
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12th May 2018, 12:35 AM #28Member: Blue and white apron brigade
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I finally got the new 3P motor back together and added the impeller and am testing it in a temporary wooden enclosure.
Preliminary results
1) The 3P/4HP motor by itself (no impeller) has significantly less vibe than the SP/3HP by itself it replaces - shall we talk about the smoothness of 3P motors? Maybe not?
2) A 50Hz the 3P/4HP with the new keyway and impeller has twice the vibe in the X (radial), slightly less vibe in the Y (90º to X) and about half the vibe in the Z (Axial)
3) At 55 Hz the 3P/4HP has a bit more vibe in the X, much less in the Y, and even less in the Z than @ 50Hz
I will do the stats and post more detail once it all done
I could not try 60Hz because the impeller is flaring and touching the sides of the temporary wooden housing. It did that with the SP motor when I first tried it in the wooden housing - I allowed about 1mm of clearance all round so it must flare more than 1mm. I then hogged a few mm out with a chisel
The SP motor with impeller draws 6A from the 240 mains cavitating air inside the temporary wooden impeller housing, the 3P and the VFD draws only 4.4A total from the 240 mains.
Pics and Data soon
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12th May 2018, 01:07 AM #29Member: Blue and white apron brigade
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Some pics to go with the previous post
This is the test rig,
This shows the old motor suspended from its blue steel base plate on top of 4 wooden legs anchored to the base plate by 2' Bugle bolts.
A 35 mm thick wooden box/enclosure, also anchored to the base plate by 2' Bugle bolts, surrounds the impeller.
The 1/4" steel plate clamped to the top of the box just gives me a feeling of security, because if the impeller were to let go nothing would hold it.
Comprig.jpg
Old motor - here you can see the spots where I had to gouge out a bit of the wooden box with a chisel because at full speed the impeller was flaring and touching the sides.
Oldmotor.jpg
Here the clearance
clearnace.jpg
Replacement 4HP 3P motor and new 6mm AL baseplate because motor flange holes are differently located.
Newmotor.jpg
Ipad collecting vibe data.
X is left/right, Y is top/bottom and Z is in and out of steel plate top
Ipad.jpg
Ipad display.
It also calculates the RMS vibe in mm - see red arrows
RMS is the , square root of the average of all the deviations squared.
I expected the X and Y (as these are both radial) vibe to be greater but of course the steel plat probably acts like a drum head.
IpadDisp.jpg
A summary o the results are in the graph below
Compare the vibe of the two motors (SP and 3P) alone (no impeller) with the 3P motor showing much lower vibe even at 55Hz.
[EDIT next day]Whoops - I just checked the 3P impeller rotation and I had it the wrong way so had to redo all the 3P measurements - I also did some other frequencies.
The 3P motor with impeller is clearly less vibratory from 40 to 60HZ. compared to the SP motor. If you don't want to look at all the little XYZs just look at the yellow bars as they are the (vector) sum or all thres
Interesting to see the X, Y and Z jump around a bit but the total increases steadily with frequency.
I'm very pleased wth this and am not even going to bother filling in the unfilled 7mm wide old keyway slot on the motor shaft
Screen Shot 2018-05-12 at 12.28.58 pm.png
Tomorrow will hog out some more of the sides of the wooden box and try 60Hz - keep clear.
The question is why do all this - Well I didn't want to install everything and find out it was a rattling bucket of bolts.
There are also a coupe of things I can try to reduce the vibe if I need to.
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12th May 2018, 09:27 AM #30Member: Blue and white apron brigade
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Anorak Bob's Photos of thursday
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