Hedwick MV100 mill looking for some dimensions

Hello all, this is my first post. I hope I am placing this in the correct subforum.

I have the above mentioned mill. My wife's grandfather bought in new in Feb. 1957. Serial # is MV175

I have had the beast for nigh on twenty years but I have not used it a lot. Something about raising children, but I digress.

It is missing a couple of parts and I would like to get some key dimensions so I can make the parts myself.

I am missing the wheel and o ring that spins the rpm meter on the front of the mill.
part numbers are mv 80134 and mv 80136

for the o ring what is the section diameter and OD or ID

For the wheel what is the OD, bore diameter and overall thickness.
Is the bore stepped or straight thru ? Material? I assume aluminum.

The other missing piece is part of the power feed clutch assy part number mv 80156. There are two of these parts. They are probably brass and they are shoe that runs in the groove of the engagement clutch.
They transmit the motion from the knob that hangs under the left side of the head that engages the clutch to the auxiliary timing pulley.
It looks like they could just be a length of 1/4 inch square stock with a side hole drilled for a dog point set screw to fit in.
If anybody could confirm that and give me an overall length of the part I would be grateful.

Bumping the thread up.

I went ahead and made a couple of brass pieces and turned a dog point on a couple of set screws.

Assembled the kit and as the Brits like to say. It worked a treat.


Still hoping somebody has info on the oring size and wheel diameter.

Hey Erich,

My MV100 (MV474) didn't come with the tachometer at all, so I can't directly answer your question. That said, it's attempting to measure the surface speed of the spindle, so that o-ring runs like a tire on the face of the cog that runs the spindle off of the toothed belt coming from the high/low speed gearbox. Based on that, I figure that it doesn't matter what the diameter of that wheel + tire is, just that it's the same as the diameter of the spot that it touches the cog face, so that they're both moving at the same speed.

Does that make sense? Do you agree with the logic?

Cheers,
Will

I do.

I finally noticed the wear path and Assumed they would design for 1:1 speed ratio between spindle and tach.

Made one and got it working. Speeds seem reasonable, but the tach does not return all the way to zero, it sits about 300 rpm when off.
Initially the shaft on the tach was very stiff, I put a little light oil on it and spun it by hand until it freed up. One of these days I will take it in to a speedo repair shop and have them service it.

Sweet!

If you ever have it apart for cleaning or changing belts or the like, I would very much appreciate pictures of the OEM tachometer. I have a tach for checking spindle speeds that I'm planning to retrofit into the head cover of my mill, but I'm not 100% sure how they were mounted and most of the owners I've gotten in touch with have a broken or missing tach, same as the machine I bought.

I wouldn't mind the dimensions you ended up coming up with, too, if you get a chance. I have to fab up that wheel and o-ring to mount to the tach I have. The DRO installation is today's project, and rebuilding the original power feed is the next major project on the list, followed by etching new tags for the machine, so no rush on it.

Thanks,
Will

Will do.

The tach has a flange on the front. It slides in through the hole from outside.
the is a U shaped strap with two holes for studs on the back of the unit and a notch to clear the center shaft..
It is held on with a couple of knurled nuts.
I will take a look on my computer to see if I made a model of the part. I might have made it from a napkin sketch.

Thanks for bumping this up. Someone reached out to me by PM and said they had an original and could give me dimensions in a few days. I replied that I would like that very much but don't go out of your way to get it.
We'll see what shows up in my PM box in the next little while.

Just started working on the MV100 I bought last year but never found the time to get it fixed and have a question on the tach.
It seems to be the original, and it seems to be working (missing the O-ring, but the needle moves when I turn the wheel). My scale is turned about 30 deg to the left side and a bit loose so I wanted to take the tach out to see if I can get it fixed. But how to get it out? I see the U strap but it is very tight in the housing and I do not see any knurled nuts. Any ideas?

I went through the tachometer problem more the 40 years ago, I remember trying a few orings on the tach drive wheel.
There were no parts, or manuals we could find decades ago. Bought the machine from Bixby in Spokane, used it for a few years, then traded it back for a larger machine.
The Hedwick was surprisingly ridged, the head tilted side to side, but didn't have the nod, because of the drive shaft to the head.
I think the mills were good, but not many were made.
IT was so long ago, I cant remember how to remove the tach, be carful, the part are easily broken.

OK, I got the tach out. The wheel with the O-ring is fixed to the shaft with two sets of tiny set screws (1/16 hex key drive size). However there are two of these set screws in each hole and it took a while to figure out that after removing the first one there is another one below. Then the wheel comes off the shaft, the hex nuts at the U clamp can be taken off and the tach removed from the front of the housing. Unfortunately the tach was not not only offset from zero, it seems to have some loose parts in it, so that is the next task.

I would locate an old fashioned automobile speedometer repair shop. They should have access to the parts and knowledge to fix the guts.

The loose parts were fortunately only the screws for the scale, otherwise the tach was fine and is working. I ordered size 328 Buna 70A O-rings and they work well with the original wheel. I had to buy 50, so in case someone is in need PM me and I can send you some.