Pulleys, motor mount and head spacer
These auto youtube/google videos crack me up, it is probably the music .
We decided to add a head spacer of 64mm to the head, that way the motor would have a better amount of clearance. I found a piece of stock 6061 that was 4x6x3" so close enough, modeled up the mounts in fusion360 simple head spacer. I had to run out yet again to lowes to grab M10 and M12 bolts, 100mm graded. Everything I think I have all the bolts, we need more. Usually the big box stores have a poor stock and they always sell in ones and twos, which is annoying especially since the barcode on the plastic bag wears out fast and checkout ends up being longer than finding them, plus the cashier and people behind you probably hate you. with all the little tiny bags of one bolt, one washer , split, nut of each size, and the pencil thing they give you to write on a plastic bag…
this thing keeps growing, not sure how much load it can carry
mmca is making the new pulleys on the HF mini lathe, i like this pulley calculator because it shows rpm and you can slide things around, we’re using a 4" 1/4" large 2" 1/4" small , approx 4" 3/8" center , RPM large is 3600
he was working on the lathe with a non chip cutting lathe bit, so it’ll often spiral out the cut and attack the operator, i was trying to catch an example on video. this is a test pulley we’re cutting to test out the process. we ended up with a bunch of these swarf aluminium tumbleweeds.
Belt Length 19~3/16"
Ratio 1 : 1.89
RPM Small 6800 Large 3600
Belt (Surface) Speed 4005.5 ft / min
Pulley Gap 1~3/32"
Using Gates 3M/5M v belts, 3M487 which is 487 mm /19.2" long
Making the top surface nice and flat, and with a HF mini lathe , that is some fun.
Cutting the pulley out.
here’s the finished pulley.
we wanted a straight hole into the pulley for an allen screw into the keyway on the motor shaft.
I used a V bottomed tap guide and a centre punch to make a pilot mark for the drill press.
To make sure i had a straight hole. I used a digital angle gauge with a magnet bass, attached it to the top surface of the tap guide, then put the tap guide onto the drill bit while mounted into the drill press, then zeroing out the gauge. next mounted the the pulley+vice to the drill, put the tap guide + angle gauge onto the top and rotated it til it was back to zero. This way the hole was being drilled from the reference of the drill itself , not the table etc.
and it worked, probably overkill but circles are hard.
also grabbed a 4x x 4 1/2" by 1 1/2" 6061 block to mill into another pulley..
for the head spacer, the 4x3x6" block needed cut down a little, so slap it on the horizontal bandsaw.
a long time later
note to self(others) set the tension first and make sure when you think, hey isn’t it taking a really long time to cut that the top isn’t sitting on top of the block. this block is 4×6" which is the size of the cutting area, but you can’t cut this size horizontally longer, has to stand up like this. I would have cut it on the bandsaw which i put a much better blade on, but we wanted the little machine to make it all the way though, unfortunately at the very end the block loosened and cut off a tad more at the bottom than we wanted.
This made the facing operation an overall 0.013" cut instead, which ended up working out really well in the end.
This step is making the soft jaws parallel with each other and more importantly the machine ,the idea being that this surface will be as parallel to the cutting surface as is possible with the current setup, then we’ll put the head spacer on it and face it, flip it and do a face pass on the other side. targeting a depth of about 2.5"
We replaced the vice jaws with soft jaws and cut a grove in each side using an offcut 1" block of tool plate as the side references.
facing the upper head spacer. cutting off about 0.002" each pass.
after the facing operation, on to the fly cutter. we were 0.1" off on the width which was a damn shame, since it meant having to move the y 0.3" then pass back and forth. This is a single point cutting tool from the lathe that makes a very nice surface finish. this isn’t for looks, we need this block to be as parallel to the front/back as possible. Any deviance will show up later when its installed on the mill and it’ll affect out our ability to cut.
before the fly cutter is run you can see the surface finish is pretty good and there is that low spot i mentioned earlier after the horizontal bandsaw it is a small defect and won’t affect the overall stability of the block, we’d rather have the girth since more Y axis movement.
here is the finish after the fly cutter operation, again .002" cut, about a dozen passes
mmca pointed out at this level you can see the variations in the ballscrew since it isn’t perfectly made so for each turn it won’t move exactly the same amount. the interference patters are neat
that was it so far, next is to cut one hole in the middle, counter sink it to fit onto the machine and drill 3 holes for the M10 bolts. this is the bolt pattern we’re following.
after measuring the corners and middle it came out to 2.54" within the tolerance of the calipers, so pretty good.
here’s the VFD
you can make a 10 5×2 idc ribbon cable to extend the control box.
the power cable, i used a dryer cable as its called here at lowes, its a NEMA 13-30P which can do single phase 220V + 125V since washer/dryers often use both. We will just be using the two 220V hots + earth/ground, no neutral. Totally overkill but the idea was to have an outlet for a welder, which didn’t work out since the sparks installed the wrong cable, but plenty for the vfd+motor and the breakers are set to the wire size.
these are the stocks for the side mounts, ready to mill.
that was about as far as we got for this day. my line laser arrived as well, this is for a scanner project.