Saturday, April 20, 2019

Hermes 3000 Replacement Platen Knobs

Large Black, Grey, Small Black

This is looking at the shaft side. Original H3k knob is on the left.

Here is an idea of what needs done to fit either of the black knobs compared to the grey one.

The O.D. of the knurling on the collar varies, but not enough to prevent using the grey knob.

The width of the knurling is just about perfect for fitting to the grey knob.

Checking the maximum depth without milling off the nib inside the knob.

Close enough for 0.200 inches (0.186" as measured)

Original knobs for the square H3k (green or white, 30mm)are just under 1.250 inches.

This black bakelite knob (at nearlty1.25") may just be a perfect fit. I will need to machine the shaft side and add a set screw to make it work.

The grey knob is a bit under size of the original knobs, but looks good, and needs no machining.

The small black knob is just over an inch.  This one only requires putting it in a V-Block, drilling, and tapping it for a set screw (5-40 x .125" or 6-32 x .125").  No problem with a drill press or a Dremel drill press.

I tested the fit on an H3k I'm working on to sell.

Looks good, at least to me.

This is what I like about the black knob. It is a metric knob and fits the shaft perfectly.

There is one problem.  A set screw is needed to hold it fast to the shaft, and it will not be the easiest to tighten due to the side place.  The plate can be loosened, but I think tightening the set screw will still be problematic.

I does look good too. Even with its small looking size the platen was quite easy to turn. I temporarily mounted it with hot melt glue on this end while letting the other end of the shaft free so I could pull out the shaft and heat it to soften the glue and remove the knob.

Here is the grey one mounted to my 1971 H3k Petit Pica Typewriter.

Comparison of a round body knob to the grey one.

Round body collars are a bit different than the ones used on the square body.
My go-to hardware supplier.  Being close to the Chicago warehouse I get next day delivery on 99% of my orders (normal shipping cost).  In fact I do not think it took more than 1 or 2 days to get an order anyplace I lived.
This was a way over due project as I have been replacing square body H3k platen knobs quite regularly for myself and others who get the square body Hermes 3000.  I even tried to create my own using InstaMorph, but I was not satisfied with the results. For more on using InstaMorph check out Magic Margin