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Installing a digital tachometer
- Thread starter Dusty
- Start date
Why ever do we men buy things and set them aside for later? As for keeping up with the Joneses I'm so far behind the curve due to my right knee surgeries and all the unforeseen problems. Presently I'm in Katchup mode not the kind that comes in a plastic bottle. LOL
As for my mid 70's canoe build, did that over a summer here in MJ for a well planned fishing trip the following spring in northern SK.
Military had other ideas by transferring our young family back to Europe. Sold the canoe and never once dipped it in water. Murphey's Law, how sad.
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I was going to suggest milling a spot in the jamb nut for the magnet but I think @whydontu suggesting a smaller magnet has me beat.
Yes-sir-re I really like that idea and it will certainly do the trick because a magnet should stick to the sides of the wrench cutout as well.
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Aw no worries. So you never used it. It had its place as a dream you once had. And building it was a source of pride regardless.
I think it's better to measure our lives by what we did do than by what we didn't do. Seems to me you did a lot more than most.
@Susquatch totally agree with you, I think that's the best plan yet for small magnets in such a tight spot. Unfortunately there's little room for a spider as the dang belt pully gets in the way of things, very tight quarters in my gear change cabinet.
From what I understand adding additional magnets, in my case having a magnet (each 4) in each wrench slot might be used. Somewhere along the way I read where additional magnets provide the sensor with a stronger refresh. My tachometer kit instructions mentions
0.2-0.5Second@120-1200RPM, and 0.25-0.6Second@2400-9999RPM.
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Thank you for your kind thoughts!
And more oddness. The Digiten tach is 12VDC supply, and the circuit board has tracks for what looks like two switches, marked ADD and SET. I can find similar tachs with descriptions that say they can be set for 1, 2, or 4 pulses per revolution. So my guess is the controller has dividing capability.
The odd thing is the one I have (also from Amazon) is 110 - 230 VAC supply, with no tracks for switches. And the AC supply version is $13 vs. $21 for the DC version. Which makes no sense, as the AC version has a transformer, bridge rectifier, and filter cap that isn’t required for the DC version.
The odd thing is the one I have (also from Amazon) is 110 - 230 VAC supply, with no tracks for switches. And the AC supply version is $13 vs. $21 for the DC version. Which makes no sense, as the AC version has a transformer, bridge rectifier, and filter cap that isn’t required for the DC version.
Ya, I agree. It makes no sense. Could it be a volume cost thing?
VicHobbyGuy
Ultra Member
Can you post a link to the one you bought. please? $13 is about half what I paid on AliExpress!
I'll be honest here. I might buy something like that on Ali if I wasn't worried about the mission. But generally speaking I like to buy such things from North American suppliers even though I know they prolly buy from China. That way I can phone and get my order corrected or whatever in very short order. Waiting weeks or months for an Ali order iteration is just plain exhausting.
@whydontu a beautiful morning here in Saskatchewan, just wished my lovely wife of 63 years happy anniversary. Yup tied the knot May 23 1959 here in MJ.
Out to my shop, measured the wrench slots on the spindle nut which comes out somewhere like 1/4 " - 6mm square perhaps a hair under. Tight area to do any kind of serious measurements.
Then I go on line to amazon.ca enter 'square magnets' searching for 1/4 "/ 6mm square magnets without success. Most likely I'm not providing the words key for their search engine also tried square earth magnets, small and mini magnets and rectangular magnets, assorted magnets etc. Loads of round magnets, assorted magnets, found zip in my search at least they didn't bubble to the top.
Open to suggestions folks.
Out to my shop, measured the wrench slots on the spindle nut which comes out somewhere like 1/4 " - 6mm square perhaps a hair under. Tight area to do any kind of serious measurements.
Then I go on line to amazon.ca enter 'square magnets' searching for 1/4 "/ 6mm square magnets without success. Most likely I'm not providing the words key for their search engine also tried square earth magnets, small and mini magnets and rectangular magnets, assorted magnets etc. Loads of round magnets, assorted magnets, found zip in my search at least they didn't bubble to the top.
Open to suggestions folks.
Try just neodymium or neodymium magnets.
These might be a tad too big.
Lots of round ones that work just as well albeit not quite as sexy as what @whydontu has. (his magnets are pretty cool too.....)
Happy Anniversary Bill. You have 13 years on me. I have one great grandchild. You must have 20!
Don't give up on the rear spider so easily. If your gear change cover has a hole in it to accommodate long stock, then you can put a spider in there just fine. It will just stick out through the cover.
Since you don't need it for the sensor system anymore, it can even be removable so it doesn't have any chance of catching clothing.
Thanks, and yes I did find the 10x10x2mm listed while searching amazon not quite what I had in mind.
Shall see what @whydontu says as to where he found the ones he has.
I wonder how hard it would be to grind them (grind a bit off of one side for a perfect fit) and how much doing so would affect them?
Neodymium magnets are sintered and the base material is flammable so they must be kept cool. Go slow and allow lots of time for cooling or use a water dropper.
Also use a good sealer or they will corrode and fall apart.
That said, here is a link to machinable neodymium magnets!
McMaster-Carr
McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
DPittman
Ultra Member
Happy anniversary Dusty. 63 years amazing. I've only been married 16 years so far and while I won't be around for another 47 to make my 63rd anniversary, I admire your commitment and success as I know there are always struggles and challenges in every marriage.
@Dusty I cannot remember where I saw it but I thought this was a good way to mount a magnet to a shaft, securely.
The poster took a piece of ABS pipe and turned it to fit snugly on the shaft. He then drilled a hole in it to accommodate the magnet flush. He then turned another piece of ABS and slid it over top of the first piece and a couple of drops of crazy glue to keep it in place. The cover sleeve needs to be thin enough to allow the spacing for the magnet but this should not be too hard. The magnets previously mentioned are strong enough. This method insures the magnet will not fly off. If everything is a slight push on fit, you should be good. And a nice little turning project with plastic.
2 cent Shawn
The poster took a piece of ABS pipe and turned it to fit snugly on the shaft. He then drilled a hole in it to accommodate the magnet flush. He then turned another piece of ABS and slid it over top of the first piece and a couple of drops of crazy glue to keep it in place. The cover sleeve needs to be thin enough to allow the spacing for the magnet but this should not be too hard. The magnets previously mentioned are strong enough. This method insures the magnet will not fly off. If everything is a slight push on fit, you should be good. And a nice little turning project with plastic.
2 cent Shawn
VicHobbyGuy
Ultra Member
VicHobbyGuy
Ultra Member
I've purchased magnets from this company and (as I recall- it was several years ago) the service was very good.
Big selection of block/cube magnets:
https://www.kjmagnetics.com/products.asp?cat=11
They have a note on Hall Sensors:
https://www.kjmagnetics.com/blog.asp?p=reed-switches-and-hall-effect-sensors
and a list of their magnets that would be commonly used with Hall effect sensors:
https://www.kjmagnetics.com/products.asp?cat=191
Most of the block magnets seem to have the correct orientation to work with a tach sensor - the main question is which have a high enough Tesla rating for the sensor pickup distance.
They have an interesting website and email 'newsletters', too.
Big selection of block/cube magnets:
https://www.kjmagnetics.com/products.asp?cat=11
They have a note on Hall Sensors:
https://www.kjmagnetics.com/blog.asp?p=reed-switches-and-hall-effect-sensors
and a list of their magnets that would be commonly used with Hall effect sensors:
https://www.kjmagnetics.com/products.asp?cat=191
Most of the block magnets seem to have the correct orientation to work with a tach sensor - the main question is which have a high enough Tesla rating for the sensor pickup distance.
They have an interesting website and email 'newsletters', too.
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