Has anyone tried to use a pre-condenser in a vertical folded build?

I am thinking the heat rising from the bulb will collect in the radius of the condenser lense and eventually make it crack as the heat and cool cycle happens a few times (projector on\projector off) The only way I can see this working is with a piece of tempered heat resistant glass between the bulb (Ushio 400W) and the condenser lens (OHP singlet turned upside down- works remarkably well)

Anyone tried this?

Here's the plan, mount the piece of glass (taken from a shop halogen work light- tempered and rated for 500W halogen) above the bulb and have the condenser rest on spacers on top of it. This will create a buffer from direct heating and allow a cooling path between the bulb and glass- then the glass and condenser. Thoughts?

Here is the plan so far.....

That should work.

Things to be aware of, though. Glass cracks when it's heated unevenly. Try not to directly cool only a part of your condenser lens, as that will cause more stress on it. If you can pass air underneath your tempered glass, that will help a lot. It would also help if that's a hot mirror, but that gets expensive.

Note that you'll lose some light to the extra glass, but with a good precondenser, you should gain more than you lose.

Thanks for your response! I should probably take some stress off by pushing cool air past the lamp Only, and use the exhaust to wick warm air away from the Condenser lens. The hope being the ambient temp around the lens will be close enough to it's own temp to cool it at a gentler rate.

Right now my projector is set up as in part 1 of the pic. I should probably change things around to resemble part 2, eh? (I havent built the condenser mount yet, so I am just doing groundwork now.) I'll probably have to find a bigger piece of glass or build a glass sled to accpomplish this.

This is a quick diagram of what worked for me when trying to maintain the integrity of crown glass lens over a 400w bulb. The 'Gaps' provided air to flow over the lens while being pulled in and towards the arc. The channel allowed more air to pass over and around the arc for more efficiency and not sufficate the fan. The box housing provided a tunnel to maximize direct cooling for both lens and lamp. Mind you, I must have gone through more than a dozen crowns due to cracking and/or turning yellow being close to the arc, so, it would make sense/cents to just purchase one that's resilient to extreme temperatures like Pyrex brands or I believe Schott glass that use silica material in it’s make up. Cost a bit more but in the long run provides less headaches and/or worries. In any case, ...do not...tighten the lens to it's mount in any way. Allow for a loose fit for expansion.

Click to view attachment

Have a gander at my lightbox in my ploD as well. Linked in my signature line. My precon is borosilicate.

I'm also working on a vertical PJ and have similar concerns. Here's where I'm at so far with my design.