Tool Life & Cost/Price Analysis

[thkoutsidthebox]

Hi all,

So I've been working on a costing program in Microsoft Excel which I can re-use for each job and calculate/output my total costs and end price, and generate a quote for any job. Its coming along nicely and I think it'll work out quite well.

The problem I have is that I dont know how long my router bits will last before needing replacement. At the moment Im using 50 hours for every type of bit. So the program is giving me a costing of about 5c to 30c per/hr depending upon the initial/replacement price of the bit.

Im only working with wood, both soft and hard and Im looking for an average bit life just for wood, regardless of the wood type.

Is 50hrs before replacement accurate? I just pulled it out of my head!

Would there be a huge differance in bit life between say a 12mm V-Bit and a 25mm endmill?

Thanks.

I have another question but we'll take them one at a time!

Edit: Im not sure if you will need more information on my tooling to help me so if you do just ask. I think most of them are HSS, some are Teflon Coated, and some might be carbide. Thanks.

[thkoutsidthebox]

Hmmm....I guess nobody knows how long their router bits last on average in wood......

[ger21]

Too busy to answer this morning. The answer is, as it usually is... it depends.

Depends on the type of wood being cut, how fast your cutting it, type of bit....

In a commercial setting, I don't think we ever get anywhere near 50 hours of tool life. Maybe 25, but probably less than that even. But if I'm cutting 10 times faster, then 5 hours for me = 50 hours for you.

Some woods are more abrasive then others, and will dull tools quicker. Some woods create a lot of buildup on the tool which generates heat. Heat is the #1 killer of router bits. If you're tools get pitch buildup on them, clean them after every use. They'll last longer.

And yes, you'll get different life from different types of tools.

Not sure if this was helpful or not. If I had to pick a number, I'd say 20 hours. But you're going to have to figure this one out through trial and error, and months or years of real use.

[thkoutsidthebox]

Thanks Ger, that is actually very helpful. I'll halve my times down to 25hrs which hopefully will help prevent me getting a shock by my tooling costs being 100% higher than expected . I haven't been cleaning my bits after use, but I will start.

Next question...same type.....I have used 2000 hours as the basis for charging for wear on my power tools, such as belt sander, power planer, drill etc.
I think this is accurate as it works out about 240 days of continuous 8hr use, which of course will never happen. Maybe 30mins or an hour of intermittant use here and there. Anyway, I figure since all my tools are brand new I should get a lot of use before seeing repairs or replacements needed.

What you think...2000hrs with fairly light use before replacement?

Thanks.

[gmfoster]

Originally Posted by thkoutsidthebox Thanks Ger, that is actually very helpful. I'll halve my times down to 25hrs which hopefully will help prevent me getting a shock by my tooling costs being 100% higher than expected . I haven't been cleaning my bits after use, but I will start. Next question...same type.....I have used 2000 hours as the basis for charging for wear on my power tools, such as belt sander, power planer, drill etc. I think this is accurate as it works out about 240 days of continuous 8hr use, which of course will never happen. Maybe 30mins or an hour of intermittant use here and there. Anyway, I figure since all my tools are brand new I should get a lot of use before seeing repairs or replacements needed. What you think...2000hrs with fairly light use before replacement? Thanks.

I think 2000 hours is real high for actual use of tools. Lets look at a car and see what the typical American car company thinks the life of a car is before is should need repairs. The average warrentee for the last several years has been 36000 miles or three years if you let it sit in a garage. So at a modest speed of 50 miles per hour that comes out to 30 days of useage. 50 MPH at 24 hours per day is 1200 miles per day. So 10 days is 12000 miles and in 30 days your warrenty is used up. 10 days at 24 hours per day is 240 hours so 30 days is 720 hours. Therefore a car company thinks thier 40,000 dollar tool should last less than half as long as you are expecting a sander to last...

2000 hours is more or less 8 hours per day for a year. I don't see how you could use very many tools that much in a one man shop. I have fornd that most universal motors(those with brushes) usually last somewhere around 200 hours of actual use at best. Sanders, routers and other tools that see sawdust constantly lead a very rough life. Now saws, planers and outher tools with AC motors ofen last nearly forever with proper care.

And router bits are usually tested as to how many feet (or meters) of wood they can cut. There have been some life tests in some of the woodworking magazines in recent years. But one thing that will kill any bit is heat and in CNC applications it is easy to burn bits by moving to slow.

Some of the above is based my low opinion of car companys and some is based on experence while other is based on what I have read, I hope some of it helps you out at least a little.
Garry

[Newby2]

Maybe this is a bit off the path but do you realize that machine manufacturers , and maybe car manufacturers base the life of their machines at 3 to 5 years. Why is that... a machine shop can amortize the cost of the machine for 5 years, write it of , so to speak.
The place I work at wants to keep the machines around for the next 20 years and will not let me run the machines at 100% rapid. He gets annoyed when I run them at 50%. But, at the same time, complaines that the machine takes to long to make the part.
So it comes to this...get the most life out of the tool, or, get the most parts per hour out of the tool.
The tool also includes the machine, for it is a tool.
Steve

[thkoutsidthebox]

Thanks folks, thats food for thought. I think Im more of the 'get the most parts per hour' school of thought. If I wanted to go slower or lighter I would buy cheaper tools.

I'll reduce my hours for my rougher tools, like belt sander, and leave it at 2000hrs for my drill etc. I think I'll reduce the planer hours aswell just because its expensive to replace when it does need parts.

I know for a full time production shop, €52 for an ogee router bit is probably not a huge amount, but Im only starting out, and part time, so thats a lot of money for something which might only last 20hrs when each job can see it running for 30mins or more. So I really want to get the most out of my bits.

Thanks again. Please feel free to add more advice/general discussion to this thread.

[ger21]

Originally Posted by thkoutsidthebox I know for a full time production shop, €52 for an ogee router bit is probably not a huge amount, but Im only starting out, and part time, so thats a lot of money for something which might only last 20hrs when each job can see it running for 30mins or more. So I really want to get the most out of my bits.

Don't run profiles like an ogee if you can run it by hand with a bearing guided bit. Most likely it will be very much faster to run by hand. You might be surprised how much lineal footage you can profile by hand in 2-3 minutes of actual tool use. 30 minutes running an ogee bit seems excessive, unless your running 500ft or more.

[gmfoster]

[QUOTE=thkoutsidthebox;258804]Thanks folks, thats food for thought. I think Im more of the 'get the most parts per hour' school of thought. If I wanted to go slower or lighter I would buy cheaper tools.



But that is sorta what you have done, you have a lighter cheaper cnc machine. And the fact that it is will effect your travel rates and this in turn will tend to burn your bits.

Please don't take this as critism of the work you have done on your router, but it isn't a multi thousand dollar item weighing 100's of pounds, allowing travel speeds in the 200-300 or even faster IPM rate. So just be sure to watch for bits burning rather than cutting and always try to cut in constant velocity mode rather than letting it dwell. And it may work better to slow down the rotation speed of your spindle some. Keeping an eye on what is going on will be your best guide. And starting a useage log like you are doing is a very positive thing and will be very useful if you can keep at it.

And as I say your router looks great and I have the plans myself, if I ever get the time. My current router has been a learning experence but is not the machine these newer hobby designs are. And my biggest problem has been burning bits.

I also second what Ger21 says about using a bearing guide and hand routing or table routing when you can. If you start making standard shaped signs you will be surprosed how fast you could do the blanks with a patern following bit and a template then do the lettering and pictures with the cnc.

And the CNC can be great for making rather complex templates..

Garry

[thkoutsidthebox]

Thanks folks, no offence taken gm. One of the items on my list is a standard router table, so when I get that I'll start doing the profiles by hand. to be honest its a bit of a pain having to do the ones Im working on now with the cnc because they are straight edged and if I had another router and a table they'd be done very quickly. But for now I think it'd be worse having to take off my router from my machine and set it up, then try to re-set it on the cnc table.

Also, like gm's first router, this machine is just for getting my feet wet and is not very impressive. But thanks for the compliment. Hopefully the next one will be running those hundreds of in per min. When I was talking about the more expensive tools, I was referring to my tools other than my cnc router.

Thanks again.

[rancherbill]

GMFOSTER

Originally Posted by gmfoster I think 2000 hours is real high for actual use of tools. Lets look at a car and see what the typical American car company thinks the life of a car is before is should need repairs. The average warrentee for the last several years has been 36000 miles or three years if you let it sit in a garage. So at a modest speed of 50 miles per hour that comes out to 30 days of useage. 50 MPH at 24 hours per day is 1200 miles per day. So 10 days is 12000 miles and in 30 days your warrenty is used up. 10 days at 24 hours per day is 240 hours so 30 days is 720 hours. Therefore a car company thinks thier 40,000 dollar tool should last less than half as long as you are expecting a sander to last...

This is calculator voodoo. A car trip for 30 days x 24 hours per day would definitely show whether there are any problems with a car, but, it would not show how long the car would last.

A 36,000 mile warrany does not mean that the car will only last 36,000 miles.

A warranty demonstrates a manufacturers confidence that there are no defects in workmanship or materials. It is also an assurance that if there are problems that they will fix them.

Warranty does not show the "expected life' or quality of an item. The expected life / quality of an item can be guaged from the price. You get what you pay for !!!

[gmfoster]

Originally Posted by rancherbill GMFOSTER This is calculator voodoo. A car trip for 30 days x 24 hours per day would definitely show whether there are any problems with a car, but, it would not show how long the car would last. A 36,000 mile warrany does not mean that the car will only last 36,000 miles. A warranty demonstrates a manufacturers confidence that there are no defects in workmanship or materials. It is also an assurance that if there are problems that they will fix them. Warranty does not show the "expected life' or quality of an item. The expected life / quality of an item can be guaged from the price. You get what you pay for !!!

If you got what you pay for they would not expect a $40,000 car to give problems after 30 days while a $40 dollar china made box fan will be warrented for a year and I can turn it on in April or May and never shut it off for 6 months and if it fails take it to Wallmart for a new one.



Quote(Warranty does not show the "expected life' or quality of an item)

Sure it does.. If they didn't expect it to break at around that time they would extend the time they guarentee it to work. If they wern't having problems that were costing them money there would be "No" reason for them to stop coverage. I have driven enough vehicles past the 200,000 mile mark to know that if there aren't manfacturing defects they will last way beyond the warrentee periood. I can install a junk yard engine in a car that is already so far gone it smokes and usually make it last longer that the new car warenty.

I lost a slave cylinder on a clutch once in 9 months and they didn't want to cover it because it was a wear item. Yea right! They finally did it for 10.00 bucks under customer satisfaction or some such... Then they wonder why I quit buying new cars....

I also lost a rod bearing on a car with just over 50,000 miles on it that had a cylinder bored so far out of line that the edge of the insert was wore to a knife edge. Definately a serious manfacturing defect and should be taken care of by any manfacturer.

There is no way any properly manfactured should have a problem in less than 100,000 miles. And no reason any company that has any pride in thier cars should settle for less. They ought to be happy to fix the problem and get to the root cause to eliminate it in future production.


And they wonder why they are having problems selling cars....

Enough off topic..

Garry