Tolerances, at what point do you start charging more

[halverson.peter]

I'm curious at what point tolerances start to become an issue. I figure that cost is the easiest way to judge this.

Using as a base, pocketing a 1/2" diameter x 1/4" hole and cutting a square 1/2" projection (1/4" thickness) from aluminum, steel, and titanium (Ti64), at what point do you start charging more for tighter tolerances? and at what point does the cost double? Also what machine are you running?


e.g.

for aluminum +-.005 and +-.010 might be the same, +-.003 might be 25% more and +-.0015 might be 125% more

for steel +-.005 and +-.010 might be the same, +-.003 might be 50% more and +-.0015 might be 150% more

[TGibbs]

Good question, alot of factors can contribute to it. I would say it depends on what machine your using to cut the features and how complex it is. The examples you gave are pretty straight forward and I would say even +/-.001 wouldent be a huge issue in steel and aluminum, assuming your machine is in decent shape and repeats fairly well. Now for titanium the story can change a little with tooling and how often youd have to replace it in orcer to hold the tolernce. Now if your machine doesn't repeat so well and you have to keep "easing" the size to be in tolerance, then thats where the up charges come into play. I woulden't do a price increase based just on tolernce, look at the whole situation, experence can come into play alot too.

Does this answer your question at all?

[beekeeper]

When working up quotes. I look at machine time, programming time to complete the part which is where you would factor in the tighter the tolerance and complexity of the part. The tighter the tolerance and complexity warrants more machine time. Then estimate your tooling needed perishable and non perishable. Once you have all this put together you can supply a quote. But quoting on tolerance alone I dont do