Cork platen for Blick 5. First prototype fail.
I prevail in being stubborn and continue messing with my Blick 5, to make it type properly with my home-made, custom type elements.
The problem I face is bad imprint. It is not related to my type elements - I see this equally well when typing with the original one. I recon that main sources of poor imprint are:
hard platen. Hardly any surprise.
poor quality inking cylinder
poor quality ink
Now, starting from the end: I use standard, round-the-corner-paper-shop stamping-pad ink. It is bad and cheap. I tried mixing it with glycerin, to get it more “substantial” but results were not much better. Richard Polt suggests using Bates Numbering Machine Ink. Not surprisingly it is now out-of-stock on Amazon but I found a shop in Germany which still has it. It’s on its way so I hope to “tick” this point.
Poor quality inking cylinder - well, after my moderate success with home-made felt cylinders (I used black-powder gun wads, punched to match the size) I switched to pre-inked, modern cylinders which you buy at paper shop. They are still being used in cash registers or calculators. While the ink in them is working well with the Blick - they are fragile and wear out rather quickly. Again, Richard Polt comes with rescue - there is a product which matches exactly spec for Blick: wool felt wads for gun care. Caliber 7mm. I bought both 7 and 6.5mm as they are quite cheap. They are on their way, too. With proper ink this combo will hopefully do the trick.
Hard platen is a constant struggle for all typewriter aficionados with limited budget. Doing rubber re-coating with JJ Shorts or similar company is a big expense. What scares me most, thou, is a possibility that the platen will be lost in transit and gone! For Underwood or Remington that can be fixed by donor machine but Blicks are not that common and not cheap either.
I know one company which uses their own couriers to pick and deliver platens/rollers from customers. But guess what - they don’t do it for free which, after adding all in total, costs roughly as much as a Blickensderfer in decent condition.
All that aside - tinkering is a pleasure in itself so I’ve decided to come with my own solution.
Putting heat-shrink tubes is a known hack. I could turn the platen down on a lathe to compensate for tubes’ thickness and have it “re-coated” that way. This is an option I want to keep as a last resort. All in all - having the original platen on Blick (mine is in good shape) is a value in itself.
Putting bicycle tube on the platen is another option which I already tried. For most machines this rubber is too soft and imprint gets too fat. The only exception from this, in my case, is my Underwood 5 which seems to like it. It prints well and sharp.
My recent restoration, Oliver 5, has cork platen. That gave me a thought to try the same on my Blick.
As this will be a prototype I decided to make a new platen and to save the original intact. Disassembling the carriage will be also an occasion to do some adjustments and cleaning.
Starting from the right side, unscrewing the bell/knob and line advance mechanism.
No need to unhook the line advance spring, I leave it dangling.
This next step is not necessary to remove the platen but I want to properly clean the carriage so I unscrew right bracket which holds the platen. Note slots on its base - these are used to adjust platen position relative to typing element, like when top or bottom of letters is printed uneven.
Carriage left side - carriage release rod and reinforcing rod (with small nuts). Carriage release rod is so long and springy that it can be simply unhooked without removing platen brackets.
It’s never too many photographs when putting apart a machine. Right side of the carriage and position of small springs before the complete subassembly is removed.
Left side of the carriage is as simple as a threaded knob and locking nut. All threads are standard, right-hand threads.
The original platen has wooden core. Central axis of diameter 5mm is most probably glued/press fitted and constitutes one part with the platen. The platen has 32mm in diameter and 248mm length (excluding shaft)
Smaller diameter of the last 7mm of the platen is to accommodate a scale for line advance. For my prototype platen I will skip that, for simplicity. It should otherwise have 29mm in diameter.
While at it - I decided to renew paper roller. It was still working but the rubber deteriorated badly.
Shaft is made of steel, no brass sheath since the roller rotates with its axis. Simple solution as on the platen. Rubber stripped revealing some surface rust.
I took care of that.
I built the new roller using heat-shrink and plastic tubing. Made it a tad smaller in diameter, to prevent it from colliding with a screw head at the base of the machine. I had this problem when typing on really thick paper. It is possible that the original roller expanded due to aging and cracking. I made a new one 2mm smaller in diameter.
Now to the platen. First thing to determine was if I have a proper threading tool to replicate original threads. I wanted to use same screws and fittings, making only the platen brand new.
I tested all my ANSI threads, UNF and UCF and none was fitting. In an act of despair I tested metric, too. Guess what - M4 is matching perfectly!
I turned a wooden dowel to 28mm diameter since the cork I will be using has 2mm thickness. The axle was made of brass, just in case M4 is not exactly fitting. In such case it will be the axle which will get damaged, not original fittings.
Drilling so long and small hole was a challenge, even on a lathe. The drill has a tendency to wander in such non-homogeneous material as wood. I drilled from both sides so any inconsistency should happen deep inside the dowel.
With the axle pressed-in the core was ready to be dressed with cork.
Now - the usual way would be to cut a strip of cork and wind it around the platen in a spiral fashion. That makes it easy and time effective and this is what I see on my Olivers which have cork platen.
But I wanted to try another, more labor-intensive way of doing it: single sheet, overlapping at edges at 45 degrees, to form a uniform surface. I’m a hobbyist, after all.
Since I chose this approach I had to glue the cork in two stages: first just the edge, leaving excess of material for later trimming. Weighted and held with masking tape the assembly was left overnight for curing. I used standard, white wood glue. Polyurethane wood glue was not grabbing the cork.
The next stage was to wrap the remaining cork around the core, exactly mark meeting edges and cut the edge at 45 degrees. I was too busy to make photographs.
The resulting roller is even and smooth. After light sanding one cannot feel the join line of both edges. It is visible, thou but not disturbing.
So how does it work?
Well, it prove to be too soft again.
The letters were deforming paper and in some cases type-element face surrounding the letter was also printed. Clearly they were diving into the cork structure together with a paper.
Put aside poor ink roller and cheap ink - this platen did not make situation better. Moreover - even though I was careful to make both axle ends concentric they ended up a bit off, resulting with variable platen position with each line advance. That resulted in the same letter printed differently depending on a row: sometimes it was perfect, other times upper or lower part was faded. Clear sign that the platen was not revolving only in one direction.
Well - what lessons did I learn?
final platen will be made of hardwood, this should prevent the axle from bending when being pushed into the wood and wood “giving in” as being soft.
the axle will be made of 2 parts, shorter. Just enough to anchor them in the core. Drilling will be then more precise and concentric, from both ends. Much shorter.
the cork I was using was too thick. And it is really not 100% cork but rather a cork-rubber composite. The problem with pure cork is that at such thin sheets it is very brittle and cracks easily when bent. It may be a bit stiffer than my chosen material but I will try again with the same material but thinner. I will also sand it to go down to ca 1mm thickness.
if that proves to be still too soft I may wrap a single layer of heat-shrink above the cork, stiffening the surface a bit.
So not all hope is lost. The story continues.