New Delta seals

[ChipRite]

I received an order of the new Delta seals and noticed that they now have a tapered hole with a narrower opening at the end. I would think this is for more pressure and vacuum.
What I picked up so far in using them is that I find more of those "dreaded" black spots in the pit of the repair. I cannot really recall having any of those for a long time while using the older tips with the bigger hole.
I am guessing that the smaller hole is putting more rubber on the glass, that in turn is pushing more of the break closed and trapping air. This must be why Delta has again mentioned the tip pressure and black spots in the newsletter.
Anyone else noticed this?

[SGT]

My experience with the new tip seals has been positive. If I were to guess, the seal inner diameter might be rounded to better accomadate penatration of the plunger. If the hole diameter is in fact smaller in might provide for a slight increase in vacuum.

As for the black spots, I think you might be looking in the wrong direction. Black spots can more commonly be caused by the glass flexing upon injector removal from excessive tip pressure. There are other reasons as well but I would contact DK for an exact answer.

[cazador]

At school I was explained the one side of the rubber seal had a small inclanation (dip) from the fabrication machine and this side goes into the
plunger. The smooth side is than the outer side, which goes on the windshield.

[SGT]

cazador,

As not to confuse anyone, you are describing the old seals. The new seals do not have this mold detent on the side. The new ones are stamped on the top and that is inserted into the injector.

[ChipRite]

Brian,
Thanks, yes hopefully Jeff will come in on this one with a comment. Today I tried all my repairs using the absolute minimum tip pressure on the new type seals and they all came out good, as before with the older seals. What I also did was to make sure that my injector was exactly 90 degrees to the glass, even on the curved surfaces, using the reflection trick. My reasoning was to make sure that the broader rubber "foot" did not have a heaver tip pressure on one side of the tip and so causing the black spots when removing the injector

It may just be my own imagination, but could the new seals be a bit more sensitive to tip pressure than the old types wrt the black spots? I will watch this carefully and will also try an older type tip again as I still have a few unused ones.
I also need to change my bad habits and lighten the tip pressure more every time!

[cazador]

When you lighten the tip pressure too much , resin will seep out while under pressure and or draw not enough vacuum. I've experienced by tightening the piston too much, leggs started running somewhat. At class I learned, after positioning the bridge, tightening the 2 back screws first , than srew down the piston until it hits the glass and follow with 3/4 turn more. Me following this procedure I achieved better fillings and vacuums !

[SGT]

When you lighten the tip pressure too much , resin will seep out while under pressure and or draw not enough vacuum. I've experienced by tightening the piston too much, leggs started running somewhat. At class I learned, after positioning the bridge, tightening the 2 back screws first , than srew down the piston until it hits the glass and follow with 3/4 turn more. Me following this procedure I achieved better fillings and vacuums !

You might want to review your notes again as I do not think they taught you that in training not even for a verticle repair! Just missing the sequence or step depending.

DK, did guys modify your techniques? Hell maybe I have been doing it wrong.

[Brent Deines]

I have been watching this thread with great interest before jumping in. For the most part I try to stay out of these conversations as I hope technicians will contact Delta Kits directly if our opinion is desired. However in this case I think I can clarify a couple of points.

If you look carefully at the new seals you will see that the end with the writing on it has a slightly flared opening, and the opposite end (glass end) is slightly tapered to form a smaller hole.

The flared opening allows the piston to enter the seal more easily, and the reduced hole size on the glass end produces slightly more pressure than the old seals. The hole is also perfectly centered in the new seals, which it was not in the old seals, and both ends have a slightly rounded edge. The round edge on the injector side makes installation easier and the round edge on the glass side helps keep the seal from flaring out under pressure.

In our testing the new seal provides a superior seal against the glass, against the injector cylinder wall, and against the injector plunger, which all help produce more consistent results in both the pressure and vacuum cycles. More consistent pressure and vacuum should reduce the chance of leaving trapped air "black spots" in a repair, however I would have to agree that because the new seal is more efficient, it may take slightly less pressure to fill a break than the old seal did.

We have sold thousands of the new seals to date, and to the best of my knowledge this is the first time anyone has commented that they liked the old ones better. Whenever we make a product change of any kind we expect some negative feedback, but based on my personal experience I was very surprised to hear anyone say the new seal was not a big improvement.

Applying too much pressure against the glass is the number one reason for black spots in a repair "after" removing the bridge due to the over flexing of the glass. Applying too little pressure against the glass can cause the seal to leak, so the key eliminating black spots is to apply just enough pressure to create a good seal without leaking.

We bring this up frequently in our newsletters because it is one of the things we frequently find experienced technicians are doing incorrectly in our training classes and learning how to eliminate the black spots is one of the skills necessary to receive a Delta Kits certification.

One more thing. Brian is right, we never train technicians to tighten the rear adjusting screws first.

I hope this helps. Thanks to all of you for the great input. I really enjoy reading your posts.

[ChipRite]

We have sold thousands of the new seals to date, and to the best of my knowledge this is the first time anyone has commented that they liked the old ones better. Whenever we make a product change of any kind we expect some negative feedback, but based on my personal experience I was very surprised to hear anyone say the new seal was not a big improvement.

Brent,
Thanks for a very clear reply. If I gave the impression that I do not like the new seals or think that it is not a good improvement, then I apologise, but that was not the intention of my thread. In fact I think the new tips are great. It was just that I noticed right at the start that there was a slight difference, possibly due to my own habits and methods and was wondering if anyone else had also experienced this seeing there were no posts on the subject yet.
I took careful note again today to square off the tip to the glass and use as little tip pressure as possible and the repairs were again great, using the new tips.
I can just compliment Delta on a great product, your B300 bridge/injector is outstanding and I have just pulled in my old (non Delta) bridge, which still uses a separate vacuum pump to be pensioned off permanently!
If not for the exorbitant exchange rate and shipping to South Africa, I would have ordered another one, but that will have to wait a year or two now!

[cazador]

I'm confused now and don't want to putt Matt his head on the block, but after setting the bridge , I screw down the piston 'till it hits the glass, then turn it another 3/4 turn as told and all is set to proceed , just apply the resin into the injector ! This means , the 2 back screws are already set and screwed down to level the bridge. I'm open for correction and change my procedure !