conrad
New Member
Goo Goo Ga Ga
Posts: 2
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Post by conrad on Nov 17, 2006 22:12:41 GMT -8
Hi, I thought I would post here, even though I have emailed Steve individually. Steve, I asked a few weeks ago if you had any info on milling clay, since then, I have got my hands on some Chavant I-307 and sourced a manufacturer with a 5-axis mill. The problem is, they are inexperienced with milling clay (as expected in small town Victoria, B.C.). So I was wondering if you or anyone else has some specific answers or know of any resources where I could find information on: -Cutter Speeds -Feed Rates -Proper Cutters for Clay -How to deal with the excess chips and how to protect/clean the mill during/after the process So as not to offend, since I know it is a touchy subject amongst modelers, I am only milling the buck to save time, detail work will be done afterwards. A machine is no replacement for human craftsmanship.
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geep
New Member
Posts: 26
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Post by geep on Nov 18, 2006 10:21:32 GMT -8
Interesting question. Machinery's Handbook is a little vague on S&F's for clay. ;D
As far as protecting the machine, the main things I would be concerned about are keeping the clay chips out of the coolant sump and protecting the ways. I would be sure to vacuum out the machine thoroughly before beginning, as you might then be able to salvage some of the clay swarf for re-use. A shop vac with a trash bag would be ideal for this.
To protect the ways, I would ensure that the way covers were tight and in good condition. This should prevent the clay from being ground between the sliding fits. I would take extra care in the case of a pressure-lubricated machine.
To prevent the clay from entering the coolant sump I would cover or plug the sump opening and stop the chip conveyor in the case of a machining center. Personally, I would prefer to do this on a toolroom machine, as you don't have to worry about as much cleanup inside the enclosure or chip conveyor. A sheet of plywood on the table would prevent the chips from entering the coolant via the table troughs and also provide some Z-axis overrun.
Just out of curiosity, why not rough the shape with drag templates? If it doesn't give away a new product, what are you modelling?
-John
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conrad
New Member
Goo Goo Ga Ga
Posts: 2
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Post by conrad on Nov 18, 2006 14:23:40 GMT -8
Good points. Fortunately, the machine is similar to a Tarus machine where the part is stationary and the cutter moves (no ways). I was planning to lay down some poly under the part so that we could just roll it up and collect the chips. The team I am designing this for is a student team at the University of Victoria that competes in the FSAE series (a design, build and compete competition sanctioned by the SAE - info can be found in the competitions section of www.sae.org - of an open wheeled 600cc race car). We are counting on the company with the 5-axis to donate machining time to us, it sounds promising. We have found someone to machine an undersized blue insulation buck to which we will add 2 inches of clay, then send that to the 5-axis to be milled down about an inch to roughly the final shape, then we will finish it. It would be nice to do it all by hand, but if we can get free machine time, it will be easier. Our team is on very tight time restraints.
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Post by Steve Austin on Nov 19, 2006 22:14:22 GMT -8
Hi Conrad, With the cutter speed you will find that this will vary according to the way the clay cuts. If you start out at medium high speed and the clay cuts without sticking to the cutter or replanting it back onto the model then the speed is OK. If it starts sticking onto the model, reduce the speed and feed to minimize heat to the cutter. This will ensure that the chips are easily brushed off of the model. With the excess clay chips reheat and use again providing there isn't any foam contaminants. If you cut the clay full, that is 2.0mm off of surface this will give you the chance to repack clay to the areas that are low on clay, then when you mill to the finished size all of the surface should be there for steeling down. If you use 5.0mm step over when machining you should get a good end result. If you contact Tarus direct they would be able to answer you specific needs for speed and feeds also they have a selection of milling cutters specifically for clay. As far as milling the first iteration of the model, that is a standard practice within the automotive industry. If time permits then it is reworking numerous times by Alias modelers with design guidance on the computer to improve the design or revised by hand sculptors. It all depends on the work load and whether the model is a concept or production piece. Steve
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