Defect in groove. Anybody else seen this?

[concretecowboy71]

I have seen this defect twice in the last couple of months and was wondering if anybody else had ever seen anything like it. It looks like a small groove exiting the side of the main groove, like a branch on a tree.

I think he playback stylus catches this and skips over to the next groove.

Here is a shot I took on my phone:
http://www.flickr.com/photos/cowboy71/5507564932/

Thanks for the input, scratching my head as to what might cause this.

[JayDC]

anyway to circle what your talking about, I cannot make it out..

[cymbalism]

On the left side of the pic it looks like a tree branch.

That's just bizarre. Never seen anything like that before, weird

[JayDC]

2 things i can think of..

A) something on your lathe is too low.. ie: your vacuum nozzle is hitting the plate...

2) there was a scratch on the blank before u cutted it..

[concretecowboy71]

I did not think of the chip nozzle. I will keep an eye out for that. Right now, it is pretty high up off the plate, but that does not mean that has always been.

I thought of the scratch thing also, but this has happened twice and both times the extra groove originates and branches directly off the main groove. It would seem that a scratch might go all the way through the groove to the other side.

Thanks for the input!

[JayDC]

that would probably be true, unless u cut through it..

I only thought of the nozzle coz i had the problem at first when i made my rear suction for the presto..

[cymbalism]

You should check the feedscrew, I had an issue awhile back on the last part of some records I made that I noticed immediately that the groove was becoming shallow only on a couple revolutions, there was some chip that had somehow wrapped around the screw which was causing liftage. Maybe your screw has something on it causing it to jump like that.

Just another thought.

[gold]

On first blush it looks like either the defect happened after it was cut or the defect was pretty deep on the lacquer since it penetrates the groove wall. It looks like a scuff. On the other hand it could be dropped chip that got stuck. Did you try blowing it off with nitrogen?

[dietrich10]

Is this on a new lacquer or one you have used the other side for cutting tests and such?

I have to razor clean my platter once a year as it leaves marks on the bottom of a lcquer which makes it unusable if I blow the good side.

[opcode66]

I use one of the paper circles that come in a box of lacquers. The suction works through the paper. I use it to cut two sided dubs. Works a treat for me.

[JayDC]

I've been playing with this anti-static "slipmat" that has a built in 3 speed strobo in the center I got from amazon.. Reduces static charge on the plates, but seems like air would pass through it, and its soft and fussy.. so it doesn't mar the lacquers.. I just pop'd a hole 1" from the center to allow the "dub pin" on the presto to come through and lock the overhead, but you guys dont have those..

[concretecowboy71]

I have been using the material that one uses in silk screening. It is soft enough where it does not scratch the lacquer but allows air to pass through for the suction to work. Has worked like a dream.

This shot is from a test pressing so this defect was in a master lacquer. It was brand new, although I cannot tell you if this was the first or second side I used.

I wish I could find the picture I took of this same defect the first time I saw it on another lacquer. It looks identical, that is why the scuff/scratch theory seems harder to go with. Plus, the first time, the extra groove perfectly bridged between two adjacent grooves without overshooting either groove. If I find the picture I will post it also.

[concretecowboy71]

Here is a picture I took in January of the same defect on another record. This one is in the lead-in groove of a 12". The first picture was on a 7".

These are very similar and could not be in the same spot on the lacquer because of the size difference in the lacquers.

Anyway, just more food for thought.

http://www.flickr.com/photos/cowboy71/5509405850/

[dietrich10]

So this is on the lacquer not the stamper or test?

[gold]

Like I said in the above post I've seen dropped chip make that type of mark.

[dietrich10]

I use one of the paper circles that come in a box of lacquers. The suction works through the paper. I use it to cut two sided dubs. Works a treat for me.

Ive had paper mess with revolutions on some batches of dubs

[concretecowboy71]

Would dropped chip show up as a groove on the test?

It does make sense though, chip originates in the groove just like the defect in the picture.

It seems that left over chip, if plated would be a bump or ridge.

[jjgolden]

Hi Concrete,

Yes, that looks like a momentary chip drop. If you notice the angle of the mark matches the angle the chip travels from stylus to suction tube.

A few things that can cause this:

1. Suction strength weak.
(Chip jar getting full, or suction tube gets blocked intermittently)

2. new/wet/soft batch of lacquers.
3. Suction tube not close enough.
4. Impurities in the lacquer
That's all I can think of for now. Let us know what you find.

Hope this helps some.
JJG

[andybee]

this looks like a scratch on the record (both pics),
but the grooves look intakt

[monkey1553]

Just curious. Is the defect in the pic really preventing the needle from tracking properly or is it just similar to one on another lacquer that was causing problems?

To me it doesn't seem bad enough to cause the stylus to jump.

~Michael