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Thread: What did you learn today?
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1st Apr 2019, 01:44 AM #721
Hi Bill, Guys,
I've long been interested in electrical things ! I hold various qualification in both electrical, electronic and mechanical engineering along with an Amateur Radio Licence acquired way back in 1971-2. So I hope that I'm sufficiently qualified to comment on these things.
However things change over time and I can make mistakes just like the next man ! My problem is not being able to keep up with the changes of the things that interest me. Indeed when I stop learning that will be the time to nail the lid on the box.Best Regards:
Baron J.
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1st Apr 2019, 10:24 AM #722Member: Blue and white apron brigade
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My experience and jobs are somewhat unusual.
Undergraduate and postgrad degrees in Applied Physics and a doctorate in experimental nuclear physics i the 1970's and early 80's
I then worked as an experimental physicist for 6 years both here and in the US where we had to design and build all manner of gear.
Then I taught electricity, electronics, sensor technology and computer interfacing, to science and engineering uni students for 20+ years.
Most of what I designed and made at work was non-standard and had limited applicability outside the lab. Not a lot of call for designing and building an apparatus for burning nano-diamonds extracted from meteorites in an ultra pure oxygen atmosphere in a shed. The only time I got to do standard stuff was at home and having access to a half decent workshop and lots of test gear at work was a bonus.
One of the most practical things I did at work was design and build ultra clean metal free labs that we could then use for sample prep. In 1986 I built a small (6 x 4 m) ultra metal free clean room at uni for preparing samples for analysing meteorites - I did the lot, design, plumbing, electrical, fume hoods, and clean air handling system. Our research group did this without asking for permission from admin and then asked for forgiveness and we got away with it - that would not happen today. Over the next 30 years was part of a research group that designed 5 more ultra clean rooms the last one being a suite of 6 labs covering some 400 m^2. This one had all manner of sensors to monitor the labs. We could even pick up if someone took their lab coats off inside the clean rooms. This is why I am able to guffaw on-and-on about dust and air flow yadda-yadda in the woodies forum.
The problem with teaching is you end up knowing how little the students know. When you are laying under a X-ray scanner in a local hospital and you know the guy driving the gear barely passed your subject you hope he's learned something on the job
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1st Apr 2019, 06:41 PM #723Philomath in training
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Not sure what happened here, but the end result was disastrous...
I had the 6mm plate pictured clamped to the table and was trimming off a strip (cutter on the horizontal spindle). I was climb milling but the mill table has an anti backlash device, so it should not have dug in like it did if that was the only issue.
My best guess is that one of the clamps slipped, allowed the cutter to pull the plate, overloaded the cutter and the rest is self evident.
P1040443.JPG P1040444.JPG
The learning here is to make sure work holding devices are tight and don't just rely on a couple of clamps if there is room for more, especially if there is a chance that the work will pull into the cutter (rather than push it away)
Bugger.
Michael
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1st Apr 2019, 06:50 PM #724Most Valued Member
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Wow that actually went surprisingly well, at least it was only the side and face cutter that went west.
Sent from my Nokia 8 Sirocco using Tapatalk
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1st Apr 2019, 07:34 PM #725Pink 10EE owner
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Looks like an artistic "feature".
Gold, the colour of choice for the discerning person.
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1st Apr 2019, 07:35 PM #726Most Valued Member
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As the cutter passed through the material what if anything was used to stop the cut area closing up?
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1st Apr 2019, 09:02 PM #727Philomath in training
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1st Apr 2019, 09:21 PM #728Most Valued Member
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You may of been lucky with the others or the characteristics of the material may of changed,generally when slitting material a timber wedge or similar is inserted after the cutter and before reaching halfway.
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3rd Apr 2019, 12:32 AM #729
What did I learn today? I was able to avoid throwing away a fan by drilling a hole!
Today I learned it is possible to save a multi speed floor fan by drilling a hole.
It is ROK brand all chromed steel model.
it began slowing down and stopped this morning.
It seems the talcum powder like dust that my cockatiel pet exudes has something to do with it.
It is fine and gets into the guts of the fan and seems to suck up any lube from the bearings which are self aligning oilite type.
I have had to throw away a previous fan because of the same problem. A $100 purchase price for a new fan convinced me to put some effort.
The motor is a two piece press fit and comes apart easily. I noticed the rear bearing is in a blind hole and the rotor shaft was binding in it making it very hot.
Prior to the rotor shaft almost seizing I had been lubing the front bearing only when it got dry and squeeked.
There was no way to acess the rear bearing for lubrication so today I drilled a 2.5mm hole in the cap cover and oiled it. Cleaned off of dust and feather down the fan is back to normal. It has run 16 hours without stopping and id still cool at the bearing cap.
You wouldn't credit how much dust and feather down was present and needed to be brushed out with a stiff bristle brush.
Grahame
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3rd Apr 2019, 06:52 PM #730Golden Member
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Stopping slots from closing ?
Yes please - a bit more about this idea please - ie when I make a toolholder for my qctp out of hot rolled steel should I be concerned about this idea or is it only for big long pieces ?
What about cutting a slot in cold rolled steel where the stresses make it curl over if you only cut on one side ? Would you never ever cut a slot in cold rolled steel due to this stress relief effect ?
Genuinely didn't know about holding a slot open as it is being cut.
Will do some googling but any tips also welcome.
SO to get onto topic - I learned today that sometimes you have to hold slots open as you cut them.
Bill
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3rd Apr 2019, 07:08 PM #731Member: Blue and white apron brigade
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Same principles applies when chainsaw milling - see the little wedges stuck into the kerf along the cut.
Not much happens till you get to the end and the cut slab falls onto the chain and it gouges great gashes across the slab.
firstcut.jpg
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3rd Apr 2019, 07:41 PM #732Most Valued Member
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Hello Bill,
from my experience I have only needed to place a wedge/block into the cut if performing a full depth/through cut, eg taking a slice off a piece of flat or round bar, generally longitudinally or when cutting a hollow bar, hope Ihave explained it enough.
Most but not all materials will move when being cut.
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3rd Apr 2019, 08:20 PM #733
Hi Steaminbill,
If it helps at all. I have done exactly this in the past and used cold rolled steel as well.
CRS was what I had at the time. I did not suffer any distortion problems over a 100mm length.
It did not work as the longitudinal forces dragged the 6mm HSS cutter sideways out of the slot I had cut for it. The bigger 8mm hold down screws in the QCTP block held the QCTP block but not the 4mm ones in the CRS tool holder.
I turned the CRS 90 degrees in the QCTP holder and still was not happy with it.
I had a bit of 12 x 3 flat and tack welded it over the slot. Just small tacks in 6 places
That stopped it sliding out. It seems the small grub screws stop it moving length ways in the slot but not sideways.
Grahame
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4th Apr 2019, 08:48 PM #734
One slightly off beat suggestion. I spent quite a few years feeding metal through Brobo and other cold cut saws. If there was any imperfection in the blade (from a minute crack at the gullet of a tooth onwards), blades which would handle thin wall tube without issue or a hint of forthcoming trouble could explode and shower the shop if they came into contact with even thin (2mm) bar. We did have dedicated blades for thicker or wider bar and yoused them for that application, but sometimes would do a few urgent cuts in light bar (say 25 x 2) with the blades for thin wall tubes.
If there was a miniscule crack in the gullet of a blade, the tooth following the crack would grab in the kerf and stress the entire blade, leading to cracking at least a sixth of the circumference out of the blade, and an extensive regrind/retooth.
I am wondering whether a minute crack in the cutter may have propagated enough for it to grab, moving the clamped piece and then shattering the cutter? That could explain why you have previously cut other pieces of the material without issue, then had this problem without any forewarning. The cracking issue generally only becomes evident when you get to conduct a post mortem after the event. Glad that there does not appear to be any long term damage to body or machine.I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.
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27th Apr 2019, 01:52 PM #735Golden Member
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small wobbler - small torch - silver solder ? YES !!!
Learning how to silver solder.
I decided to have a go on some small stuff. Too expensive at the moment to buy the bigger torches recommended for silver soldering jobs.
Worked fine. Am putting on far too much solder. Looks horrible straight afterwards all brown and purple and black stains but cleans up nicely.
The little wobbler runs on air at approx 1800rpm - cap doesnt fly off - so that means the cap is soldered ok - am unable to turn it over with lung power alone, my previous engines were all capable of turnover by breathpower.
So ........... novices take heart, your standard average garden variety small propane torch is capable of silver soldering small stuff and the horrible purplebrown stains wash off. My torch shown in photo called Solder Station.
In the Stan Bray book (LINK) he has specifically designed a far bigger boiler that he says can also be soldered with these small propane torches.
Bill