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Old 1st Mar 2021, 5:38 am   #1
Sebastian51
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Default Ekco A22 Black Knobs

I am looking to purchase a set of two Ekco A22 Knobs in good condition. I am willing to pay the price.

Alternatively, if someone can create a true reproduction, I am also interested in purchasing.

Best,

Sebastian51
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Old 1st Mar 2021, 10:29 am   #2
David G4EBT
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Default Re: Ekco A22 Black Knobs

I think your best option would be to try Ben Djikman in the Netherlands as he supplies a wide range of knobs and I know in the past that he's made some for other round Ekco models:

https://www.bendijkman.nl/index.php?...oduct&ipath=15

As to someone who can make a true reproduction, I guess someone who is able to do 3-D printing could make the shapes of the small and large knobs, but from what I've seen of items made even on very expensive industrial printers, the finish wouldn't come close to that or the originals.

There are lots of youtube examples of people who have cast knobs, but they all fall at the last hurdle by trying to drill an accurately concentric mounting hole after the knob has been cast. It will invariably not be concentric and the human eye can easily discern and offset of under 1mm, (which would cause an offset of 2mm from side to side on rotation).

As a hobbyist woodturner, I have actually made reproductions of a small and large black knob, using the knobs off my brown Ekco A22 as a pattern. I did it in part because a know-all fellow woodturner said it wouldn't be possible to make the small knob due to it having a tab, so I went ahead and did it all the same. However, it takes about a day to make just one knob, so it simply isn't possible to make them for others. No doubt a professional production turner would make them rather more quickly than me but as a hobbyist, I dance to my own tune.

It's a time consuming multi-stage process, but it may be that if you have a friend who is able to use both a metalworking and woodworking lathe, or a local Woodturning Club who might take the job on, that would be a possibility. I turned the knobs from beech, and sprayed them with acrylic 'ebonising spray'.

The processes I used were as follows:

Cut a circular blank of beech (a hard close-grained timber) on a bandsaw.
Put the blank on the lathe and true it up to the outer dimension of the knob rim.
Use a 12mm end mill in the tailstock of the lathe to drill a (flat-bottomed) hole to the correct depth into the beech blank into which to insert a brass ferrule.
Turn the brass ferrule inserts on the lathe, 12mm outer diameter, 1/4" inside diameter. (The original ferrules were 13.5mm diameter, fixed with 2BA screws but I used 4BA)
With the outside of the ferrule roughened up, apply epoxy adhesive to it and force it into the wooden blank.
Turn a mandrel on the metalworking lathe from 22mm diameter steel or alloy, with a 1/4" shank onto which to mount the beech blank.
Drill the side of the beech blank to insert a screw to hold the blank on the mandrel to turn the blank to its final shape.
Sand the blank on the lathe, apply shellac sanding sealer and sand to 220G.
Remove the knob from the lathe, spray with high-build grey primer, then several coats of acrylic ebonising spray.

To get the dimensions to be accurate it's necessary to stop the lathe to check several times with callipers at each stage.
(It's an easy task to remove wood, but impossible to put it back on).

The same steps are needed for the smaller knob, with the added requirement to make and fit the little tab into the knob.

I've attached some pictures, and you might find the sketches of the knob dimensions helpful.

I'll add some more pics to shown the end result.
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Last edited by David G4EBT; 1st Mar 2021 at 10:47 am.
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Old 1st Mar 2021, 10:35 am   #3
Leon Crampin
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Default Re: Ekco A22 Black Knobs

David, I have a black A22 which has an incorrect tuning knob. I managed to find a good brown replacement, and painted it with black Humbrol gloss to match the other two. Unfortunately it's a bit too glossy. Could you give any recommendations as to how I can achieve a better match?

Leon.
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Old 1st Mar 2021, 10:45 am   #4
David G4EBT
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Default Re: Ekco A22 Black Knobs

Some more pictures of the Ekco A22 knobs.

Pic 1: Large knob mounted on mandrel partly turned to shape.
Pic 2: Large knob finished and sanded, ready for spraying.
Pic 3: Small knob, turned the same way as the larger knob, but notched, and ready for the finger tab to be glued in place.
Pic 4: Completed new black knob with it's mounting mandrel, alongside my original brown knob.
Pic 5: The replica large and small black knobs alongside the original brown ones used as patterns.

(The numbers on the pictures are from the illustrations on an article I wrote that was published in the BVWS magazine in 2018).

Once more, I regret that it isn't a task that I'm able to take on, but I hope that maybe the information and illustrations might be of some assistance.

Good luck in your quest.
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Name:	Pic 20 Small A22 knob notched ready for tab to be glued into place.jpg
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Name:	Pic 21 Original large & small Bakelite knobs with wooden replicas on right.jpg
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Old 1st Mar 2021, 11:03 am   #5
David G4EBT
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Default Re: Ekco A22 Black Knobs

Quote:
Originally Posted by Leon Crampin View Post
David, I have a black A22 which has an incorrect tuning knob. I managed to find a good brown replacement, and painted it with black Humbrol gloss to match the other two. Unfortunately it's a bit too glossy. Could you give any recommendations as to how I can achieve a better match?

Leon.
I used Chestnut Ebonising aerosol Lacquer which is widely used by woodtuners and woodworkers to create an ebony appearance. The finish is satin, rather than gloss and to my eyes at any rate, it had the same appearance is did the original brown ones, (apart of course from the colour). A it's acrylic rather than cellulose, it will tolerate being applied on top of other paints. If you leave the Humbrol in place and spray over it, it would be a good idea to roughen the Humbrol with 0000 grade wire wool to provide a key for the new finish.

It comes in a 400ml rattle can, and is a bit expensive just for the odd job:

https://www.machinery4wood.co.uk/CHE...IaAuR0EALw_wcB

I guess a cheaper alternative might be satin black spray such as this, but I haven't tried it:

https://groveshop.co.uk/gti-aerosols...MaAgnHEALw_wcB

Hope that might help.
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Old 1st Mar 2021, 11:41 am   #6
Gabe001
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Default Re: Ekco A22 Black Knobs

I have no experience with this myself, but antique furniture restorers use fine steel wool to "dull" new polish and get it to blend in with the rest of the item.
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Old 1st Mar 2021, 2:14 pm   #7
Leon Crampin
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Default Re: Ekco A22 Black Knobs

Thanks David, I'll give it a try as my set is otherwise perfect.

Leon.
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Old 13th Mar 2021, 5:02 pm   #8
Stuart R
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Default Re: Ekco A22 Black Knobs

Sebastian, you have a PM.

SR
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Old 14th Mar 2021, 4:49 pm   #9
dakster
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Default Re: Ekco A22 Black Knobs

I have purchased a set of AD65 knobs from Ben Dijkman and the quality was excellent. If you email him and ask, he may be prepared to make a batch for an a22 but he would probably want a firm commitment for half a dozen sets initially.
Personally can’t see the demand isn’t there.

Last edited by dakster; 14th Mar 2021 at 4:51 pm. Reason: Typo
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Old 14th Mar 2021, 5:18 pm   #10
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Default Re: Ekco A22 Black Knobs

what i would give for an A22,great looking set ,just reading David(G4EBT)text about making replacements,all very interesting ,clever guy for sure
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Old 15th Mar 2021, 2:24 pm   #11
Ben_Dijkman
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Default Re: Ekco A22 Black Knobs

Hello .
For a costumer from the U.K we have order for 2 new knobs, those with the lever.
If more people are interested it would be good to inform us about that.
Perhaps that way , we can make a small badge of these knobs.
That way the costs a.p. can be reduced.

Best regards,
Ben Dijkman
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Old 15th May 2021, 9:25 am   #12
Ben_Dijkman
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Default Re: Ekco A22 Black Knobs

These are the first Ekco 22 knobs that we have made for our costumer.
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