G0516 Tachulator Installation
The Tachulator
In preparation for the installation of a DC motor and variable speed controller I thought it would be a good idea to install a tachometer. Once the DC motor is installed...I would have no way of knowing what the approximate speed is...thus no way to calculate SFM. I first saw the Tachulator in Home Shop Machinist and thought it would be a good addition to just about any mill, lathe or other variable speed shop tool. I chose to buy the version with all the goodies and in the die cast case. This unit cost right at $100.00 US and comes with one sensor and a 9Vdc wall transformer. Here is a picture of the "almost finished" product. I've still got to make an angle mounting plate, run the power....and install an on/off switch.
Choosing the location for the sensor
I decided that the spindle shaft would be the best location. If you remove the 4 hex head bolts from the top spindle cover you'll find a nice open compartment with lots of room, easy access to the spindle and plenty of mounting options.
Measuring the Spindle Diameter
The spindle shaft in this location measures 1.34". You'll need to know this when making your optical reflector strip.
Making a bracket for the sensor head
I chose to make the sensor bracket out of a piece of 1/8" aluminum plate. In later pictures you'll see why the bracket is angled as such. The sensor has a long slot in the center to allow forward and backward adjustment. Place you hole carefully. No sense placing the hole so far back that the bracket face would stick out past the sensor face.
Making an Encoder strip and testing basic functions
The Tachulator can be programmed (4 position dip switch) to look for as few as 1 or as many as 16 transitions around the circumference of your spindle. (or other device) The manufacturers documentation indicates that the low RPM accuracy is much better if you use 10 or more segments. Using only one transition per 360 degrees cannot guarantee accuracy below 50 RPM. Using 10 gets you accuracy down to 5 RPM and 16 segments gets you down to 3 RPM. I would recommend at least 10 segments. I simply took the diameter of the spindle times Pi to get the circumfrance....divided that by the number of desired segments, drew it up in Visio and used my ink jet printer to make the strip. (I've posted a PDF file of a 10 segment strip which you can download and print if you would like...check the links to the left.)
I used some scotch tape to mount the test strip and I temporarily mounted the bracket to the lathe using a couple strong magnets. (The test strip pictured in this image is only a 5 segment)
I connected the wires according to the silk screening on the Tachulator, plugged in the 9v power source, turned on the lathe...and wha-la....520RPM. I checked my belt configuration to see if I was in that range....and sure enough. I dialed up 1" diameter and checked the SFM.....RIGHT ON THE MONEY.
At this point....I'm thinking....."this is cool".
Drilling and Tapping
Now you'll need to drill and tap a few holes to permanently mount the sensor bracket. You'll want to remove the power, unscrew the front switch cover and make sure there are no wires in the way. Wouldn't want to drill through a wire and create another project. I placed a paper towel tight against the frame and secured it with a few strong magnets. This will keep any swarf away from the spindle. Drill the holes far enough away from the spindle so that you bit will punch through into the switch area. (This just makes tapping easier) I chose to use a couple of 10/32 pan head screws. Match this to a couple of holes on your bracket...and you're all done but the screwin'.
Bracket Mounted and new 10 segment encoder strip installed
I made a new 10 segment strip using the method mentioned above and attached that to the spindle using clear packing tape. Be sure to clean off any excess grease from the spindle.
Mounted the bracket using the two 10/32 screws and positioned the sensor close to the strip. I also had to change the dip switch settings on the controller...from 5 to 10.
I fired up this new configuration and noticed that the readings were erratic. I immediately figured this was due to the reflective properties of the packaging tape. A simple skewing of the sensor by a few degrees to the left or right solved that problem. Double sided sticky tape would probably be the way to go.
Ran some basic tests, put the shrink tubing over the wires and routed them down through the existing grommet and into the front switch area.
I couldn't quite decide how to route the signal and power wires....so for now I drilled a 1/4" hole through the face of the front switch cover and connected the signal wires to the unit.
Now to work on making an angled bracket and routing power to the unit. I'm also thinking of installing some 4 pin DIN connectors to make a quick disconnect for the sensor. This will let me move it over to the mill with ease. (another project...another day.)
Thanks for reading.....I'd enjoy any comments.
Making the base
I took a 1" piece of aluminum plate....cut a 10 degree angle slot in the plate at the width of the Tachulator enclosure
Making the base continued
I drilled holes to match up with the Tachulator Power and signal chassis holes...Drilled and tapped a couple of 10/32 holes for mounting the chassis to the base.....
Making the base continued....
Only thing left is to put some non-skid material on the base....
I have some neoprene that might work...hmmmmm
4 Pin Mini-Din connector
Well the DC motor upgrade is 90% complete. I've added a mini-din connector to the Tachulator harness and placed a surface mount din socket on the faceplate of the lathe
Plugged in...
Just a simple shot of the Tachulator connected to the Mini-Din socket.
(I think I'm going to make a new front panel. I want to remote the DC motor controller controls back to the front of the lathe. That makes me think "just include the Tachulator as part of the panel.....damn that would be sweet!...Only drawback.....can't use it on other machines. Oh well.....It's only money.)
Variable speed!!!!!!!
Here is a shot of the lathe running 41RPM. The v-belt is connected to the 3rd slowest factory setting.
Variable speed!!!!!
Here is a shot on the same v-belt setting with the DC motor at 100%. 734 RPM. On the lowest speed belt setting...I can easily run this thing at less than 10 RPM.