Question about Machine time! Using Aspire Trail version

[Blacknbart]

:confused:
I'm stuck on the Machining time given for cutting this Adirondack chair design that I conjured up to help me understand the Aspire program. The time was 01:34:10 and am I correct to read this as Hour:Minute:seconds? Should it take this long to cut? This is all hypothetical and I was "fake" cutting this design out of a 48'' x 96'' sheet of Birch at .5''thickness. The Tool Path Summary listed .25 End Mill bit, feed rate 100 in/minute, Plunge 30 in/min with the Spindle rate at 12000 RPM. I just wanna rough cut this design can I speed up the feed rate and RPM's to make it cut faster? Having to cut this in a hour in a half seems ridiculous. I've attached a .DXF file for your review. :D

[Gary Campbell]

Bart...
Your feed speed may be a little low for my tastes, but non knowing what machine you are going to post to, I cant say to increase. Pass depth will double, triple or quad the cut times, so they may impact sheet cycle times more than your feed. Rapid speeds make a difference if there are a large number of cut geometries.

Out of the box, machining estimates are usually not very close. It takes some actual cutting and adjustment of the built in multiplier to get them accurate for your machine. Based on the info you posted, I wouldnt even venture a guess if the times are accurate, half or double what you might expect.

I have cut similar parts from four 5/4 by 6 Ipe deck boards. 3 passes with a 1/4 single O @ 5ips. Took about 35 min.

[Gary Campbell]

Bart...
Assuming the cut times are accurate, have you cut these using a band saw or similar conventional woodworking machines? The guy I cut for said his took over 2 hours.

[Blacknbart]

I just read a thread on Wood Web and adjusted my RPM's to 18,000 and the Feed Rate to 400 IPM. The time now to cut my design is 23 minutes. Could I cut it faster? I actually spent the last two hours researching RPM Rates on Acrylic, MDF, Plywood, and Sintra (PVC). It looks as though I will be getting creative with my trial version of Aspire.

@ Gary,

I haven't thought of cutting this out just yet, I was just using it as a mock up design for my self training on the Aspire program. I actually have a dozen or so designs mocked up in Job scenarios to help me list actual numbers for my financial plan. Some of these scenarios are based on signage, cabinetry, furniture, and some specialty prototype items. It's been a learning experience and I am looking forward to running my own business when the time is right. Thanks for the help and if there is any other information feel free to lay it on me.

[Gary Campbell]

Bart...
You dont say what machine you intend to cut this with. 100 -200 ipm are attainable with a standard, 400 can be done with an alpha, but you may not be completely happy with cut quality, especially if cut from solids.

You will also be hard pressed to find a 1/4" bit that will single pass anything at 400ipm. I feel your last scenario is almost unreachable unless you have a very well tuned machine and better than average hold down.

[myxpykalix]

Bart,
I think you may be surprised at the differences from digital vs real life in cut times regardless of what program you use. THe variable between materials/bits/type of machine/design program will make your cut times vary widely like Gary explains.

And his point about cut quality, even if you attain top speeds is right on.
There are many guys on here (like Gary) who have fine tuned and souped up their bots for max performance and so they have done all the things you want to do, so their experiences and opinions are on the money.

There comes a point where if you push the limits you court disaster, like broken bits, ruined material, ect.

If you are just starting out i suggest when you get your machine you take it slow and not be so concerned about spitting product out as fast as possible till you get some experience under your belt.

After all, before any of us got our drivers license we started out riding bikes!:rolleyes:

[ken_rychlik]

I think a LOT of people that buy a cnc think it will be like magic and buisness will flow their way. The biggest hurdle you will face is keeping the machine running for a profit.

Learning to create things and cut them is childs play in comparison.

If you watch the for sale section you will find a lot of machines that didn't create the magic that was intended when they were purchased.

I don't mean to rain on your parade, but I do have a suggestion for you. Create a product by hand and try to sell it for a profit. Make sure you have secured lots of sales for this product and a waiting list of customers. Then buy the machine to run the parts for you.

My machine has easily paid for itself, but I needed parts cut by a machine that would free up my time.

Good luck.

[michael_schwartz]

Start cutting using conservative numbers and get your product out of your shop into the hands of customers. The worst thing that will happen is that you will have more orders than you can keep up with and you will have to optimize production. That will be a good thing if it happens :D

Work in small batches (as close to 1 unit as possible! google lean mfg and Toyota production system) and audit the actual measurements of the parts, actual cut times, actual time for setup/bit changes, etc... Before you cut the next unit you can tweak your files to improve quality and efficiency based on the previous unit.

If a file is taking longer to cut than it should I don't charge for the extra time.

[adrianm]

The vectors in the DWG file are very messy on the curves, if you go into node edit you'll see hundred of nodes which will generate hundreds of little movements in the code. You'll save some time by cleaning those up and converting to arcs wherever possible.

Don't forget when comparing machine time to manual time that you can be doing assembly while the 'Bot is cutting. Hard to do if you're cutting by hand!

Some jobs I do would actually be much quicker on the table saw but being able to do two things at once swings it in the 'Bot's favour.

[bleeth]

Bart:
I am assuming that you re-nested the parts for cutting in Aspire. Assuming something like 3/4 plywood this should cut on a standard PRT in less than 1/2 an hour and on a new Alpha in 10 minutes.

[Blacknbart]

Rain, Sleet or snow my parade keeps marching on! I can take it as well I am well aware of the state of the economy and how business is not so plentiful, It’s doesn’t hurt to plan. It’s actually really fun. I have 20 odd years of design and manufacturing with in the packaging, consumer goods and signage industries. I figured I would take some practical designs and or concepts and try to price out the materials, work, and finishing to come up with cash flow analysis. I actually have some real life numbers and some numbers solely based on research. I do understand that in real life I will have some hang ups, but I am trying to record a perfect job scenario so I can get my financial plan built. Which helps in breaking down each “Job Scenario” to find out all the in’s and out’s in order to make those numbers justified. I really like the fact the Aspire has a free trial, it seems like I do have a machine to work with and it’s helping me with my research. If I was to own a ShopBot I would have an Alpha series because of its flexibility and power. I would like to thank everyone for the support and answering my questions.

@ Gary Should I calculate a using a wider bit like a ½’’? I do need to do some research on what bits to use on the various materials I am using in my scenarios.

@ Dave if I was using an Alpha what RPM and IPM would I use to achieve a 10 minute run time? I did reconfigure my RPM to 18,000 and IPM to 400 to achieve 23 minutes runtime on the Aspire trial program. Way better that the 1 hour and 30 minutes. Curious I couldn’t find the RPM rating for the HSD 4HP High Frequency Spindle. Any recommendation with literature about HSD spindles so I can have a better understanding?

[bleeth]

Depends on bit size and how much you want to chew off at once and vacuum.
Based on good vacuum a 3/8" good quality 2 flute bit you would probably do it at 6ips cut, 16+ (depending on how much nerve you have watching the gantry move like a bat out of h----)jog, cut most of the way through on first pass and cut the skin on the second. I plunge conservative at .5 and wouldn't bother ramping or leading in on this design.
Believe me that different geometry bits from different companies cut differently. A Vortec chipbreaker would allow more speed then an Amana 2 flute compression, for example. This type of final tweaking comes from experience with tool. Even with the "science" of CNC it is still artisan work and over engineering without experience can become mental masturbation real quick!
Personally I rarely use a 1/2" bit except for very thick material cutting-Others do.

The first time someone defined business plan to me he kept using the words "fiction" and "wet dream"