Cutting Speed, Charging for Machine time

[blake_koehn]

I have a PRT with the slower board. I have an opportunity to develop a working relationship with a local company cutting some parts, mostly basic parts out of 3/4 sheet goods. Some birch ply and lots of MDF.

I am wanting to upgrade to the faster control board soon but cannot spring for it just now.

Here is the question, How fast can you consistantly cut the above materials with the faster board.

I think I will bid these parts based on the machining time in Aspire. But I know that if I base it on the slow cutting speeds that I am doing now it will probably be too high. I don't mind eating the difference until I can get the new board.

I am a newbie so if I am going at this all wrong please point me in the right direction.

Also what kind of hour rate do you put on your machine time.

Thanks
Blake

[dray]

Hi Blake. I charge fairly low in my opinion..

$100 hr for design and $100 hr for machine time + hourly for the guys working in the shop +30%

I would do some test runs to see the amount of time required then go from there.

[cmagro]

Blake,

I have had a few opportunities to cut various parts from sheet goods (same as you..birch and mdf). Most of the cutting was for a cabinet company.

I just charged by the sheet...this was not a full time thing and I had a pretty good idea as to what was being cut so I knew (on average) how much time it would take to do the drawings / toolpaths, load up the material, cut the sheet, minor touch-ups if needed etc.

Some sheets were for larger components 5-6 per sheet and others had maybe 20 components. I use a PRT like you (no upgrade yet...just a router too). I pretty much just figured for a $15 sheet of mdf I'll cut what you want for $150 (example only..you need to decide what works for you).

Whenever they needed something cut I would do a layout on a 4/8 sheet and let them know how many sheets I had to use. Sometimes I made out great, sometimes I made out just good...always made out ok at the very least.

For carvings and the fancy stuff I think it's a different story but for sheet goods it's worked out good for me.

Keep in mind that once the first sheet is cut and you have started the second sheet you are getting the stuff that has just been cut ready to go out the door. In my experience I have actually lowered the cutting speed to ensure that the rhythm of what I'm doing while the bot is cutting is timed so that we both (the bot and I) get done at approx. the same time and efficiency is maximized. Once I do anything to make the bot faster I'll no doubt have to adjust the way I work to keep that rhythm working right.

Christian

[dubliner]

Good topic & timing. I'm getting ready to embark in the same direction. Would it be reasonable to use the estimated machine time to get a figure in mind when giving an estimated price?

[jamesgilliam]

Neville, I have tried to use the estimated machine time and found it to be off by about 1/3 sometimes. If the customer sends you drawings to quote from like I have had mine do, I just let the machine do an air cut above the table to get close to the correct time. I usually start this in the evening and by the morning it is finished.

[erik_f]

You can adjust the multiplier in the estimator on Partworks. This way you can figure out how close or far off it is after a few jobs and adjust it to it will give you a pretty close idea +/- a few minutes.

[nick]

James...I too had a problem with the estimate times compared to machine times and found it to be off by 1/3...just like you...

But now...I tuned my VR setting and now my standard /w spindle is faster that the estimate times...and it now working awesome...I can get a true cost for 3d work anyway...

hope this helps