Advice on Increasing production Feed & Speed HARD MAPLE!

[Kirk Quesnelle]

Hey Everyone,

I have an Axiom Precision AR8. I produce with it a bunch of boxes that are kind of neat. Ring boxes, guitar pick boxes etc.
They are done with maple mostly.

I have the opportunity to wholesale these boxes. I'm very new to CNC so I'm wondering if some of you more experienced guys can help.

In the photo I've attached you'll see the hard maple ring box. I need to increase the speed in which a box is made in order to be profitable with making enough
boxes to make wholesale worth it.

Currently it takes about 8 minutes to produce one box. I need to get this down around 4 minutes if possible.

I'm using 1/4" upcut spiral.
100 IPM - 16,000 RPM (I feel like this is too fast?)

A lot of time is spent on the pocket.

I'm wondering how fast I might be able to run with the hard maple, and what speed.

Would love to hear your thoughts and opinions as to how I can speed up production.

rbox.jpg

[Gary Campbell]

Kirk...
Take a piece of scrap and increase speeds until the bit breaks or the machine will not hold tolerance, reducing the edge quality. You might try a 3/8 compression bit also, they will cut a lot faster than anything 1/4"

[Brian Lamb]

Assuming you are using two flute end mill, that's .0025" shipload per tooth, depending upon the depth of cut, that might be a bit light, I cut metal at that rate. I can't tell from the picture how big your pocket is, but a larger end mill will take less passes and probably be able to be pushed a lot harder/faster. What sort of path are you using to get the pocket whittled out?

[Kirk Quesnelle]

Gary, your advice is always so good. I like this idea. Then i'll know the limits. I will also try a 3/8th

Brian, I am not at the shop right now and I don't have vcarve installed at home. I did try a half inch box core mill that came with my Amana kit.
I was able to cut the pocket time in half which was great.

And yea I think I should be running quicker. I'm going to try this tomorrow and see how far I can push it as Gary says.

I will post my vCarve paths & details tomorrow

[Gary Campbell]

Kirk...
The first thing you need to be aware of is that you are using a tabletop machine. Bit mfgr's chipload specs will in most cases not apply. They (chipload specs) are for big iron machines.

You will need to pay attention and find the limiting factors for your combo of bits, machine and materials. Those limiting factors will be the material, bit, hold down, horsepower, the machines ability to withstand force and edge quality. Think of them as a chain with a weakest link. Or a teeter totter with speed (force) on one side with quality on the other. As force goes up, quality goes down. As you increase cut speeds and find and improve each weak link you will then move up to the next one. Just like the boy with his finger in the dike.

To me "normal" cutting would be using a bit with its diameter as a cut depth. What is important is what speed you can cut and maintain a reasonable tolerance to the vectors and have an acceptable edge quality. Some manufacturers claim cutting speeds that could only be attainable in air. (Axiom is not one of them) Unenlightened purchasers make the misassumption after reading those mfgr specs and recommended chipload settings that they should be able to cut at those speeds. Not true. Ain't gonna happen on a small machine.

You may find some improvements in speed, but you may simply have to settle for slower cut speeds to maintain quality. Small machines simply cannot withstand the force of aggressive cutting with larger bits. Nor can they do it all day every day. There are very few sub 4 by 4 machines that are production capable.

[Kirk Quesnelle]

Ahh very well said..

As I learn more about CNC, I'm starting to learn the limitations of this smaller machine. Sure it does small stuff well for our business and makes cool stuff but
as this part of our business grows, it's becoming hard. I'm realizing just how valuable something like vacuum hold down would be, or auto tool change.e

I've been looking at an axyz machine. They're HQ is about 1.5 hours from me.

My quick thought was I could optimize enough to get enough wholesale orders in to then justify buying a more professional machine. I'm not sure that is going to happen as fast as I'd like

--

Hey, let me ask you this. Given that I had say 100k to buy a top of the line production machine. How much of throughput are we talking in terms of IPM?
I'm running the AR8 at about 100 IPM. What could I expect from a real production CNC?

[Jim Becker]

Kirk, relative to your question about "going large", depending on what you plan on making, "large" isn't necessarily the physical size of material such as 4x8 or 5x8 or more, although having a big bed can open up the opportunities to bigger jobs dimension-wise. In the context of what I believe Gary was speaking, it's even more about "large" as in "beefy"...the build of the machine to industrial heft to be able to withstand the stresses of faster production and to be able to handle cutters in the same manner. There are a whole bunch of CNC machines on the market that sport larger physical material beds, but don't necessarily have the "beef" to handle heavy work load. Finding the right mix for what you want to do is the task if you decide to move up from the desktop machine.

One small reason that I made the purchase decision to move beyond the "desktop" format was the advise I got from Keith Outten around how things are built in the machines. Even though I'm taking a risk in the larger investment, I determined that having the beefier machine would at least support more capability and options to monetize the machine. I actually was originally going to buy the exact same machine you are currently using...it's quite nice, quite capable, packaged in a complete way from the start and priced attractively. Honestly, it likely would do everything I'll probably be capable of handling for awhile with the learning curve that I'm sure you're quite familiar with! But I anticipated that I'd be hungry for more sooner, rather than later, and given this will be my retirement business, I'm going for it.

I'm not sure how things work for businesses in your geography, but have a conversation with your accountant about how best to invest in the business that seems to be taking off for you so that you maximize your opportunities and minimize your costs, including taxes. Some creativity could get you into the machine that will get you where it sounds you want to go...which I expect you'll want to do once Gary answers your question about capability.

[Frederick Skelly]

"A lot of time is spent on the pocket."

Hi guys.
I don't know anything about CNC, so please disregard if this is a dumb idea..... But as I read this thread, I wondered if you could reduce the CNC time required to mill the pocket by pre-drilling your blank with a forstner bit? Then put the blank into your CNC machine to finish the box?

You'd need to build a couple jigs to ensure fast/proper alignment and registration of the blank when you move from the drill press to the CNC. And you'd need make a lot of blanks at one time so the drill press operations are efficient as possible. Otherwise you won't reduce the TOTAL production time per box.

It's just what came to mind. Perhaps it will give someone a better idea.

Good luck!
Fred

[Jim Becker]

Fred, in some CNC work, it's not uncommon to use a similar technique by utilizing a larger tool to "clear" the majority of the pocketing area before switching to a smaller cuter for finishing and detail. Manually drilling out with a forstner bit is something that could be effective with a slower hobby CNC, but for production work, that kind of setup wouldn't save any time. Kirk is trying to reduce his production time from 8 minutes to 4 minutes...and that's for the whole box. Even a tool change may challenge that unless he can cut multiples in the same run, which is why he's interested in increasing feed rate and hence, reducing cutting time.

[Kevin L. Waldron]

Personally would not go bigger for such a project........takes a lot of pennies to make dollars........ not impossible......But!! It will take a long time to make a large amount of money......... Consider a sub-contractor like "Brownwoodinc.com" for small items.

If you were to purchase a larger machine consider multiply head etc. to increase production....... there is a physical limit even on large machines and their capability of what they can do in a 12-24 hour period of time. Another thing to consider is material supply, waste/by-product .......how you going to get rid waste....... many more factors come into play when increasing volume other than producing........ We were offered several opportunities to increase volume far beyond our current production and we considered......... city zoning, raw material, waste/by-product, handling/packaging, additional employee's, parking etc..........We also thought about the company hiring us...... how easy it would be to simply walk away for a cheaper competitor and leave us high and dry...... Money was not our problem as far as purchasing other material but we did not want to make a bad investment. Ultimately we choose another path and have done well.

[Jim Becker]

If you were to purchase a larger machine consider multiply head etc. to increase production..

That or something with an ATC...

[Kirk Quesnelle]

I think Kevin is right. I think i'm going to shy away from the large orders. At first all i could see was $ signs without considering the amount of "other things" you don't think about.

It's much more profitable to keep doing it for my gift company and be happy with that.

Thanks everyone for the great advice!

[Bill George]

I guess what I am wondering for detail you need to run a small bit and for just hogging out material a larger one. How does having a bigger machine with a 3 Hp or larger spindle change that? A .125 inch bit can only run so fast a feed rate, same as a .250 without breaking the bit or burning material. So with a large commercial machine unless your taking a lot of material off in one pass, say with a .500 inch bit your still limited in speed?

Kirk, in your case can you make a jig to hold maybe 8 or 10 or whatever of your project. Then do the hogging or interior of those all in one set up? Change bits and do the next phase? Setup time, at least for me anyway is a bit time waster, If I am doing name tags for instance on the laser, I make a jig so the next one I drop in or more than one I can just press START and its done.

[Jim Becker]

Bill, even with the same .25" bit turning at the same speed, the force on that bit engaging the material as it moves can be substantial and that force gets transferred to the machine. A heavier machine can absorb that force better than a less substantial machine so you can run the cut speed closer to what the bit can handle rather than backing off to insure that there's no deflection of the gantry and it's associated mechanisms. More spindle power, just like with "regular" routers, can help keep the cutter from getting bogged down as it moves faster on the heavier machine. It all works together. Of course, hogging out with a larger cutter is a very common thing. The trade-off when making smaller objects is the tool change time and time is the OP's major consideration. And ATC or multiple spindle setup can help with that, of course. ($$) One other way around that is cutting multiples as you state so tool change time is done once and spread over a bunch of objects, but that's not always supportable, especially with boxes.

This is a really good conversation, BTW...and very material to anyone who's intent is to monetize their CNC to the most efficient extent.