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ecdez
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2018 POTD Thread Archive
- Thread starter 2volts
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Did the same thing for my truck. I've replaced the handle for the rear suicide door of my extended-cab truck one or twice a year, it keeps failing the same way, and it's about $40 for the replacement non-oem part, finally decided to make the handle out of metal, It's only been 6 months, but doesn't feel like it's going to break anytime soon...
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- Nov 14, 2014
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Some welding practise:
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Project I did a few days ago was to build a magnetic hall sensor pickup. This uses a small IC embedded at the tip, machined the body and the nuts out of aluminum. It is designed to be used with a MachTach Tachometer system.
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Is there a reason you made one from scratch instead of using one commercially available?
I had a MachTach kit delivered yesterday.
Nice work
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Hi Jeff,
I prefer the hall senor over the optical in most cases, you can also get the machtTach with a slot optical sensor and a gear tooth sensor. This sender is for Paco's Acra 1640 machine, I built the MachTach and used one of the Chinese magnetic hall sensors I had left over from another system which I used a smaller sensor. We are having some issues with the sensor being somewhat erratic at times, so I decided to use the small IC chip that MachTach provides, but they are fragile and not easy to install. I use the same IC on my lathe and it works well. I decided to build a more traditional hall sensor threaded body and embedded the sensor/wiring at the tip. You need to be careful not to short or break the leads and the sensor is positional so I have an index mark on the threaded body for the rotational orientation. The magnetic hall sensors typically have a sensing range of around 1/2" but it can be affected by other steel parts that can become magnetized or issues with the flux fields which is what I believe we are seeing in Paco's system. I have another sensor which is a shielded type, so we will see which works better.
The MachTach seems to be a bit more sensitive to electrical noise and requires some tweaking to work with the sensors, at least in my experience with them. Also if you use shielded cable to the sensor, do not ground the shield at either end, the VFD noise through the ground shield will play havoc with the readings if grounded to the machine. The magnetic hall sensor needs to be triggered by the north pole of the magnet, and at least on my test bench worked better with the sensor to magnet distance of around 0.1-0.15". If you have a compass, the north pole of the magnet will swing the needle to 0 degrees, the south pole to 180 degrees.
Mark
I prefer the hall senor over the optical in most cases, you can also get the machtTach with a slot optical sensor and a gear tooth sensor. This sender is for Paco's Acra 1640 machine, I built the MachTach and used one of the Chinese magnetic hall sensors I had left over from another system which I used a smaller sensor. We are having some issues with the sensor being somewhat erratic at times, so I decided to use the small IC chip that MachTach provides, but they are fragile and not easy to install. I use the same IC on my lathe and it works well. I decided to build a more traditional hall sensor threaded body and embedded the sensor/wiring at the tip. You need to be careful not to short or break the leads and the sensor is positional so I have an index mark on the threaded body for the rotational orientation. The magnetic hall sensors typically have a sensing range of around 1/2" but it can be affected by other steel parts that can become magnetized or issues with the flux fields which is what I believe we are seeing in Paco's system. I have another sensor which is a shielded type, so we will see which works better.
The MachTach seems to be a bit more sensitive to electrical noise and requires some tweaking to work with the sensors, at least in my experience with them. Also if you use shielded cable to the sensor, do not ground the shield at either end, the VFD noise through the ground shield will play havoc with the readings if grounded to the machine. The magnetic hall sensor needs to be triggered by the north pole of the magnet, and at least on my test bench worked better with the sensor to magnet distance of around 0.1-0.15". If you have a compass, the north pole of the magnet will swing the needle to 0 degrees, the south pole to 180 degrees.
Mark
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Mark
Thanks for the detailed explanation.
As far a using a shielded cable but not grounding it on either end would negate using a shielded cable, would it not? I have in the past twisted the wires to help in eliminating noise. This is my first experience with MachTach so I thank you for the info. I will put it on my mill with a 3 ph VFD motor upgrade.
Let me know if this fixes Paco’s problems if you would. I’ll be watching his thread.
Jeff
Thanks for the detailed explanation.
As far a using a shielded cable but not grounding it on either end would negate using a shielded cable, would it not? I have in the past twisted the wires to help in eliminating noise. This is my first experience with MachTach so I thank you for the info. I will put it on my mill with a 3 ph VFD motor upgrade.
Let me know if this fixes Paco’s problems if you would. I’ll be watching his thread.
Jeff
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Durn! Beautiful tool. I hope BGHansen sees your post. I'll be he could use such a punch when fabricating Erector Set parts.
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ecdez
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Thank you much.
I think I've seen his erector sets. I know I've seen punch presses go for cheap so even if he doesn't have one it might be worth it if he's making them in any quantity.