Scallop Shell

Don Baer

Moderator
Staff member
Don, I used a 1/4 ball end mill for roughing and finishing. I used a 1/4 end mill to cut out. Feed at 250 IPM, RPM at 16000. Took 53 minutes. I could have run at 350 of 500 to save time. I also could have changed stepover from .020 to .030 or more to save time. I could also change the roughing from DOC of .1, to .2 or .3 to save time. I also could change the roughing stepover from 75% to 90% to save time. Lots of room to change things. The thing with feedrate is acel and decel. You never get to max feedrate anyway. Even with that said, I am sure I could cut the time to 1/2 hour or less without trying too hard.

With things like this I like to start slow and tweak it up.

If I make these to sell, I will definitely make it go a lot faster and make a dozen or so at a time.

Bill, Thank you, I am happy with it.
Thanks, Leo, I'm not to worried about saving time I plan on an hour for doing each half of the submarine hulls but I would like to save time on finishing afterwards. the step over seems to be to key to getting the finish. If it ever cools down enough I'll play with the setting and make a run to see how it comes out. I have the designs done for 2 of the 5 classes of boomers submarine. I want to run them before I spend any more tme on the other designs but I am NOT gonna run the CNC when the temps are over 110 degrees. Life is to short and I ain't going anywhere.
 

Leo Voisine

Member
Messages
3,991
Location
East Freeetown, Massachusetts
Don, Time is money. As a part time retirement business I do have an hourly shop rate to achieve. So, time relates to sell price, at least for me anyway. In order to get to a marketable sale price I need to be able to make money doing it. Yes, at one hour of machine time, maybe I can sell it, but that is not all of the work involved. There are set up times with sanding, sand blasting, painting, and assembling a hanger. Then there is time to do the actual activity of sanding, sand blasting, painting, and assembling hanger. Don't forget the cost of materials like sanding belts, sandpaper, paint, hanger etc. The set up time gets amortized over the number of pieces being made. Making multiples also reduces cost. One more thing is the cost of selling, fees, time to package, advertising, time to post, and other things.

So my first one is a prototype to get a feel for how it goes.

If just doing it for the fun, not for profit, then time doesn't really matter, then no issue there.

For me, it is still as much fun to make but I add the enjoyment of adding the efficiency, just because I like that and also the added benefit of making a decent hourly income, and not selling at a McDonald's wage.

As an engineer, at work I set up a spreadsheet so I could calculate cost. I do the same at home. I created an Item Master, BOM and routing to capture all the cost involved and add in a material markup and labor cost. I input all of the time and materials and run up a total sale price automatically into the Item Master. After that I will consider "value" and adjust sale price UPWARD accordingly - never adjust downward.

I just found a new youtube channel about a young couple in the Houston Tx area. They are building a furniture making business and making some really good youtube content about their venture in business. Very good in my opinion.

A lot of what I do is related to this venture of a retirement supplemental income business. Much like Rennie is doing. I can "survive" without it, but the extra income helps the bottom line.

Aside from all of that, I do find enjoyment in all of these things. I enjoy the business side of things as much as making stuff. I am constantly learning and researching.

That's just me, and I know it's not everyone's cup of tea.
 
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