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Author Topic: saving a 1980 KZ750 twin  (Read 67526 times)

Online irk miller

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Re: saving a 1980 KZ750 twin
« Reply #260 on: Jan 29, 2017, 18:51:51 »


The foundry I have access to is operated by the sculpture department at my college. As a grad student I get a pass to do pretty much anything I want; interlope into other programs and departments. Its awesome. That being said, this foundry pours metal maybe 6 times a year for the sculpture students so there is a VERY loose/crude process established here.  Typically sculpture doesn't need to "work" so a lot of things that would make castings unacceptable for industry use are widely tolerated here. I blew their minds when I showed them how to do a "face coat" with chopped fiberglass in the investment. That should inform you to the caliber of work they are turning out. I asked for their advice on gating and started talking details and got blank stares in return; its something I know little about, them as well. I did one cover per investment to keep the investments physically smaller. I have only done the plaster/silica investment once before, the other times I had access to ceramic slurry investment which is much better IMHO. The castings moved around a bit and there is porosity throughout. Its not too noticeable unless you inspect close up. I would not expect them to hold oil but its for the ignition cover so its good enough.


The expense to run a foundry class has limited the ability to teach it and much of the knowledge has been lost as a result, save for what people can find online.  For the most part, schools have shuttered programs, so to find a functioning foundry at a university at all is an achievement.  In major cities or areas where there is access to commercial foundries, the process stops at wax positives in the studio and a professional foundry casts the work.   I taught it for years, but we shuttered the metal foundry at Temple University in 2009 when we moved Tyler School of Art from Elkins Park to the main campus in N Philly.  We didn't include a metal foundry in the Sculpture program in the new facility and instead, all casting shifted to the Glass and Ceramics programs where I taught.  One exception is in Metals/CAD/CAM (Jewelry) programs, but that type of metal casting typically occurs in kilns or with torches.  It's unfortunate. 

Offline advCo

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Re: saving a 1980 KZ750 twin
« Reply #261 on: Jan 29, 2017, 19:03:02 »
Very cool. I have been contemplating doing some cast covers for the 360 using 3D printed masters. Definitely some good motivation here.


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Online irk miller

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Re: saving a 1980 KZ750 twin
« Reply #262 on: Jan 29, 2017, 19:11:01 »
The castings moved around a bit and there is porosity throughout. Its not too noticeable unless you inspect close up. I would not expect them to hold oil but its for the ignition cover so its good enough.
Did you use flux and degassing tablets?

Offline doc_rot

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Re: saving a 1980 KZ750 twin
« Reply #263 on: Jan 29, 2017, 19:15:57 »
Did you use flux and degassing tablets?

negative.

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Re: saving a 1980 KZ750 twin
« Reply #264 on: Jan 29, 2017, 19:32:09 »
You have about a 3 minute window to pour aluminum before hydrogen forms.  Drossing flux and de-gassing tablets are pretty important when you don't have the equipment to de-gas. 

http://www.ebay.com/itm/N406-Sodium-Free-Dross-Cover-Aluminum-Flux-1350-1470F-/250663652557?_trksid=p2141725.m3641.l6368

http://www.budgetcastingsupply.com/product-p/2011-010.htm

Offline pacomotorstuff

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Re: saving a 1980 KZ750 twin
« Reply #265 on: Jan 29, 2017, 19:42:44 »
I was so mesmerized by the castings, I forgot to ask you what silicone rubber(s) you used and I gather, did a vacuum debulk on the rubber before you made the moulds?
Pat

Offline doc_rot

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Re: saving a 1980 KZ750 twin
« Reply #266 on: Jan 30, 2017, 02:16:04 »
You have about a 3 minute window to pour aluminum before hydrogen forms.  Drossing flux and de-gassing tablets are pretty important when you don't have the equipment to de-gas. 

http://www.ebay.com/itm/N406-Sodium-Free-Dross-Cover-Aluminum-Flux-1350-1470F-/250663652557?_trksid=p2141725.m3641.l6368

http://www.budgetcastingsupply.com/product-p/2011-010.htm
very interesting


I was so mesmerized by the castings, I forgot to ask you what silicone rubber(s) you used and I gather, did a vacuum debulk on the rubber before you made the moulds?
Pat

The rubber was leftover from another casting project, hence the two colors. I used Smooth-On's PMC line, I chucked the containers and don't remember which ones specifically. I did not use a vacuum.
« Last Edit: Jan 30, 2017, 02:20:55 by doc_rot »

Offline doc_rot

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Re: saving a 1980 KZ750 twin
« Reply #267 on: Feb 01, 2017, 04:44:59 »
I got the calipers mounts fitted. Should I do pocketing or holes? holes will be faster, but pocketing will be stronger. both will look cool.
« Last Edit: Feb 01, 2017, 04:46:51 by doc_rot »

Offline teazer

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Re: saving a 1980 KZ750 twin
« Reply #268 on: Feb 01, 2017, 22:47:43 »
Shoot Doc, that's a Brembo P08 if I'm not mistaken.  One of the very few calipers that was around in 72 and still good enough to be used today.  Or a Grimeca copy at least.  I can't read the cast in name.

Offline doc_rot

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Re: saving a 1980 KZ750 twin
« Reply #269 on: Feb 01, 2017, 23:55:47 »
Good eye, indeed it is the P08, I like the old school flavor and you can get them brand new for $130. You may already know this, but it's a semi replica of the lockheed brakes that were common on 70s racers. In fact the lockheeds were standard on the venerable Kawasaki S1. A simular Lockheed design came stock on some triumphs as well but they were cast iron bodies and pistons. I actually have two of those OEM calipers and they weigh a 3 times as much. I have the Grimeca replicas on my kz1000, and the Brembos are definitely nicer
« Last Edit: Feb 02, 2017, 01:25:48 by doc_rot »