3/4" Baltic Birch in a single pass?

Hi Everyone,

I’m in the market for a 4x4 CNC router. I’ve been running an Axiom 2x4 Iconic CNC for a few years but I’ve just about had it with its 150 IPM rapid feed rate. It’s SOOO SLOW! Also it seems pretty under powered with the 1 HP spindle. It was fine to learn on but I’m ready for graduation.

I’m currently debating between an Avid 4x4 or a Onefinity Elite.

I process mainly 3/4" baltic birch. My question is: Is full a full 18mm depth of cut possible on the Elite Foreman if I’m using a good spindle(probably PwnCNC)? I know and have seen proof it’s possible on Avid but I have not seen this proven on the Elite Foreman. I would of course build a very sturdy table for the Elite Foreman to eliminate any integrity issues there.

I want to buy once and cry once here. If the Elite Foreman will do what I want then I can save some money, but if not I just want to know the limitations up front. I saw the Lets Break a CNC Machine video. I was screaming at the video “Go Full Depth!” lol. Those feed rates are amazing though.

Thanks for reading,
Travis

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How soon do you need the machine to be up and running?

I’m not rushing anything. It will take as long as it takes. I just want to do this right from the beginning.

I am a happy owner of a Woodworker upgraded to X50 with a Masso G3 controller and Jianken ATC spindle. I basically built it all myself and only the Onefinity frame is stock. I am happy with the machine for what I am using it for, and at the time it was definitely the best machine for me in this class.

I had considered the AVID machines, but being in Canada the cost to get one here is too high. I am watching the launch of a new CNC model from another Canadian company - preorders won’t ship until July though. It is close to what I had planned to build myself, except I would use another Masso to control it.

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You’ve definitely beefed up that OneFinity! I understand the costs of shipping across the boarders. We operate an online business and deal with international shipping. Freight across the border is nuts.

That said I would venture to guess the investment you’ve made to get the OneFinity to the point it is now would be comparable to an Avid machine with similar tolerances/capacities. My price of an Avid in the States that is. I understand you probably got a lot of enjoyment out of the build of the machine though which is certainly worth something.

My internal debate continues lol. Thank you for your feedback @TMToronto

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Who is the new launch with if I can ask?
Pat

With respect to your specific question - which I realize now I did not answer - my rigidity testing on my machine would have me say that although the machine could cut at that 18 mm depth (I assume you mean single pass), you would need to limit your feed rate if you needed accurate cuts without spring passes to compensate for deflection. This may not be practical for the use you have in mind, nor how fast you need to produce parts.

I look forward to hearing from others with real experience with the exact model you are describing.

I am looking at the Sienci Altmill.

Thanks
Interesting
Pat

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I have the Sola Fide Designs KC, ATC spindle set up on a Onefinity Foreman. Frankly I am still in what I would call the acceptance testing phase.

I would put this on par with a 4x4 machine from Avid, ShopSabre or Stepcraft (Q404). I am afraid my shop space limits me to a 4x4 layout.

My machine actually uses a spindle from the same manufacturer as Stepcraft.

Could this machine plow through 3/4 baltic birch… that would be my guess. But I would also guess the cut could be pretty gnarly. I would expect to see similar results on the aforementioned machines. My desire is to have a finish coming off the machine that requires little to no sanding.

I am currently playing with Home Depot pine … you know the fast growing difficult to machine stuff. I have a standard test case of a Gottshall block. My intention is to use HEM (high efficiency machining) techniques while machining, with the intention of reducing overall machine time. Follow on test will use the same Gottshall block model in walnut/maple/oak, plywoods, hdpe/delrin and aluminum. Needless to say this will take a while.

I should also say, I owe my wife a coat rack & 4 end tables made out of quarter sawn oak.

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I would be very interested if someone created a video regarding the most efficient cutting of 3/4" plywood on a 1F Elite. This will be my primary use case. I think the video is warranted since so many people will cut plywood on the machine and the information would translate down to thinner sheets. Has anyone seen anything like this? Showing cut paths and semi-complex profiles timing the required cut time?

I think you need more definition in your request. Are you simply asking to cut out parts from 3/4" sheet goods? In this case you are doing a profile cut with an optional breaking of the edge with a chamfer or radii. Let me say that ploughing through a slot is some of the worst loading you can give your machine and bit.

Or are you asking about say making drawer sides, where you will be milling:
- dovetails
- finger joints
- variation of the quarter quarter quarter approach

By the way doing this sort of testing for a person who is not making money on the deal (and hence biased) is time consuming and expensive. Let alone the hassle of video production… I am learning Kdenlive now.

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Good point.

I am cutting parts out of a 3/4" sheet. These are 2D contour paths. Here is an example. Width of the 3/4" sheet blank for scale there would be around 45". My concern here is my old Axiom machine takes FOREVER to cut these pieces out of a sheet. I mean like a couple hours which is ridiculous. I just want to make sure the 1F could cut the parts out in a reasonable amount of time even if multiple passes(DOF) is required. Does anyone know approximately how long the profile cuts here might take? What would be a reasonable DOC and feed rate for something like a good quality 1/4" compression bit? If I knew that I can simulate in Fusion to estimate operation time.

Ok now I have a better idea.

Referencing the video https://www.youtube.com/watch?v=yJlqD5Hi3QM

His criteria was not breaking the bit or his machine. He followed a well published rule of thumb, cut no more than one diameter in depth. In his case .25" dia so .25" depth of cut. You want 3/4 inch depth so that rule implies a 3/4" dia. This would cause an increase in raw material used, just for a wider cut. I also think the material holding approach would need to be beefy.

His surface finish at 850 ipm is as I suggested rugged.

But no tool breakage :wink:

You mention a compression bit. By definition you have a down then up cut area on the bit. If your first pass depth exceeds the down cut portion then the top surface see ONLY the upcut bit… and you will see more tear out.

Are you drilling or milling the holes? I will assume you are milling and I hope you are not peck drilling (hard on bits) but rather using a helical cutting action.

Can I assume you are running 2.2 Kw (3 hp) spindle? If not, are your cuts being starved of power?

Everything I have talked about is machine independent. While I love my Onefinity, will it out perform your Axiom by enough measure to justify the cost … I somewhat doubt it.

If you want to increase your speeds may I suggest:

  • Having a 3 HP spindle
  • Install a tool changer … use the right bit for the job
    * A scoring cut followed by a more aggressive cut maybe appropriate.
  • Drilling rather than milling the holes … can your spindle slow down enough to drill.
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Thank you so much for your feedback.

The CNC router I have currently is an Axiom, not Avid. I am shopping for a new Mill currently but it’s a large investment I prefer to only make once. I do not want to be disappointed with the purchase and have to upgrade again. I have already learned on a low grade/incapable machine and am ready to finalize the machine I work with for years to come. This thread is really verifying that the 1F Elite will do what I need. I would prefer to purchase a 1F over an Avid machine simply because of the cost difference(nearly half). I will invest in a 2.2K water cooled spindle and understand that additional expenses will add up(I plan vacuum hold down, and possibly an PwnCNC in the future). Bottom line I don’t want to go with a 1F and still have to upgrade again later.

Hey Travis,

I think if you really want to drive the bit more faster through the wood, I would take a strong spindle and a larger bit diameter, and make a roughing pass first and a finishing pass after that.

Here is a video where they mill with 110 ipm, but it’s a 8 mm (5/16") roughing bit and it’s black locust, one of the hardest woods. Should go through softer woods at higher feed rate.

The other question how will your edges look like when you go that fast. If you say Baltic Birch, do you mean plywood? In this case you can’t go as fast as with other types of material. Anyway, the question that Carl and Lynn already brought up, is do you want to cut so that the edges are fine, or do you want to do a chamfer step after cutting the pieces out. Also in general it is good to do a roughing pass first, which can be faster, and then make the cut slightly larger with a finer tool, which will be faster too because it removes much less material then.

Also I would not mill that deep in one pass. The formula Carl and Lynn gave you above is fine.

this video shows not the actual velocity with which it runs, just to what feed rate it is set. Therefore this test is worth nothing. Would be nice if you could see the real velocity while it runs through the wood. Without this you would need to take a video editor and mark each pass to see the seconds a pass really took. And if they simply wanted to show that the machine won’t break, I think I need no test like that, because it’s not the machine that breaks but the deflection of the axes (mainly the Z axis) and the deflection of the bit that are the problem if you don’t choose an adequate feedrate, matching the spindle power and the bit diameter. If you use a stronger spindle and a larger bit diameter, you will experience less deflection or bit breaking than with a weaker spindle and a smaller bit diameter.

If you have a really strong spindle and a large bit diameter, it’s the stepper motor speed that can be the limit. Stepper motors (both open or closed loop) loose torque very quickly at a higher speed. If you want a faster machine, and your spindle and bit diameter are already strong, you need to use servo motors which can be ten or more times faster as stepper motors.

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Thank you very much for the feedback. All of this information helps tremendously in spec’ing the right machine for my needs.

Give me a little more time. I think I was were you are about 14 months ago. I am currently putting together a video on my machines runout. Which comes out to be about 3/4 of a thou. (Inch)

I you have a community college near by and can take a class do it. The folks here mean well but … Ok let me put it this way I am mechanical engineer, but I am only a journeyman machinist.

I will be going over the decisions I made in buying my machine. I am a cheap bast&$@ but want good value for my money

So my advice learn a lot more.

One of the concerns I have is the 1F Z travel. I have had to use ISO 30 shorty tool holders because of the 1f’s short Z travel.

If you are going to run your machine hard I strongly suggest the ISO 30 spindles. Now let me say if I could afford a cat 40 spindle I would use that. Look at a comparison of tool holders and you will see what I mean.

Basically in order of stiffness (rigidity) it would go something like router (Makita?) < ISO 20 < ISO 30 < Cat 40 < Cat 50

I have some graduate level engineering papers that describe the importance of tool holder rigidity.

@CandL I have watched a couple of your videos on Youtube already I believe. Looking forward to seeing more.

I’m an electronics engineer and software/firmware developer. Growing up on a farm however I also have “street smarts” when it comes to mechanics. That said mechanical engineering has always fascinated me.

I have already done quite a bit of research on spindles so I know exactly what you are saying here.

Bottom line I’ll be batching parts out of 3/4" Baltic Birch plywood for a project I’m working on. I believe it will be quite popular amongst woodworks and while it will be completely open source(all plans included) many people don’t have access to a CNC to cut out the parts so I wanted to offer kits for the unit to those interested.

Thank you for keeping this conversation going!

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You could easily calculate the time it takes to cut out the pieces on the Onefinity.
Let’s assume you would use an 1/4 inch or 6.35mm Endmill.

For a reasonably good surface I would go with a feedrate of 5 m/min and a depth of 5 mm which is probably pushing it on the Onefinity. So you need 4 passes to cut 3/4 inch / 19mm plywood. Maybe you can get away with three.

So you machining time would be 3 or 4 (passes) x length of all corners divided by 5 m/min (or 200 IPM).

Feel free to change those numbers, but I am not sure the Onefinity is sturdy enough to go a lot faster and still deliver good surface quality.

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