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DIY Vacuum Wand Slit

Posted: 24 Apr 2018 15:34
by Porkypig
Hello everyone - I need to pick the brains of those of you who have made an Okki Nokki type wand.

My first attempt at DIY'ing a RCM and I'm almost there.
I've fashioned a wand from 15mm pipe with an elbow connected to PVC tubing, a laboratory Drescel bottle as a liquid trap, and then on to 32mm attachment to a vacuum cleaner. Naturally I've tried to seal any leaks to achieve maximum vacuum. I'm using a 'Henry' vacuum cleaner to trial it here at work and results are promising - Except..... a 'haze' of liquid is left in the grooves so the record is still wet. The wand seems to travel flat across the surface of the disc.

The slit cut in the wand is rather crude, (not having a Dremmel) using some 2mm drill holes and a sharp knife. Then thin strips of Self adhesive felt (not velvet) applied to each side.

It could be the case of too weak a vacuum obviously but my question is - what is the optimum width of the slit for maximum uptake? I've seen varying images on the web and the Jury's out. I think the residue gets left on the felt so wets the record. It evaporates naturally after a time, so leaving some residue behind.
Before I have another go at Wand Mk2 and/or investing in another vacuum, maybe I'm doing something wrong at the Business End?
Thanks in advance for any suggestions.

Re: DIY Vacuum Wand Slit

Posted: 24 Apr 2018 19:34
by Debs
The slit on the Okki Nokki arm is 2.5mm x 93mm.

Re: DIY Vacuum Wand Slit

Posted: 25 Apr 2018 22:42
by Porkypig
Many thanks for the info Debs.
Today I constructed the second wand as before - paying more diligence to the gap. I made many more 2.5mm drill holes along the 93mm (no Dremmel as mentioned) so a labour of love for half an hour. May need to file the gap a tad more for 2.5mm, but it looks much better. The plumbing seems sound as I tested for air leaks under water ( no....I didn't get the Bends....)
I Decided to seal the end with a rubber bung cut flush to plug the end. Epoxy sealed it overnight so will test once this is dry tomorrow.

I'm looking at possibly using velvet or a mesh-like cloth as the buffer to the record surface instead of felt. Maybe this will dry under vacuum more rapidly under vacuum?

Why not just buy a RCM? My pal of nearly 40 years has just got one last month and swears by it. Fair play to him, but it looks like something that can be replicated for little cost and a bit of fun as well. But ask him to undo a few screws to reveal it's inners though ...nah...... " I'll invalidate the warranty".
Friendship eh?

Re: DIY Vacuum Wand Slit

Posted: 25 Apr 2018 23:18
by Pscm
On my diy unit I used the soft side of Velcro for my buffer. Never had an issue with scratching.

Re: DIY Vacuum Wand Slit

Posted: 29 Apr 2018 21:43
by ripblade
Part of ensuring good vacuum pressure is to make sure there's plenty of airflow into the slot. This could be done by putting the gasket only one side of the slot, the side following the slot as the record is rotated. This also helps prevent cross contaminating the records by ensuring the gasket remains as clean and dry as possible.

A slow RPM on the platter is also helpful to ensure full drying and minimal abrasion of the lands.