# 4th axis questions



## Nicky

Hello All,

I'd first like to say that I'm not a professional, woodworking is a hobby. I've recently retired and will be spending more time in my shop.

I want to purchase a cnc machine for hobby work. I am leaning towards the Genmitsu CNC Router Machine PROVerXL 4030. I plan on using the cnc for inlay work for small boxes.

I have made some chess pieces in the past and find the lathe work to be very time consuming. I thought that maybe a cnc with a forth axis could help make the pieces (rough out) much more consistent then I could on a lathe. I enjoy the detail work more then the lathe work.

I know the cnc I want is not a production machine. I don't have any experience with cnc machines, just looking to get started.

Your thoughts and advice would be most appreciated.


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## Mike_D_S

Just to clarify, you're asking about 4th axis,but the machine you reference is only 3 axis? I assume that's intentional.

I've got minimal 4th axis experience, but for things like chess pieces I would think lathe pattern jigs are the easiest solution for general consistency.

For starter CNC this machine is reasonably priced, but the Amazon reviews are a bit mixed. For the same dollars you can get the small Shark they sell at Woodcraft and I think you'd have better support in addition likely being able to see on in person potentially before buying.

Mike


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## Lazyman

A 4th axis is not always necessary. It is possible use 2 sided 3D machining technique to carve some pretty elaborate chess pieces for example. Here is an example demonstrating how to do it with Vectric Aspire. It can be done with Vcarve too but it doesn't have as many tools for dealing with 3D objects.

EDIT: Here is a 2 sided tutorial using Vcarve which is much cheaper than Aspire.


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## Nicky

Thank you for your replies.

The model I referenced has an optional 4th axis. I will look at the shark. The support is an important aspect.

The 4th axis is not necessary. I have the time to play around, and don't know how mature the technology is. Thanks for the links, I will check them.

=nick


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## Lazyman

I have an older model CNC Shark ( V3 I think). One thing that I don't like about them is that they lock you in to buying only their accessories. For example, you can buy their 4th axis electronics add-on which basically adds the port to the circuit board (makes sense) but you cannot activate it in the control software unless you buy the actual 4th axis from them too so you cannot buy what may be a cheaper or better add-ons. Theirs 4th axis may be just fine. I just don't like being locked it by artificial constraints and I have seen much cheaper options. Same goes for the touch plate. A touch plate is a very simple device which you can make yourself but you have to spend $100 for theirs in order to activate it in the software and another hundred to activate another feature that uses it to adjust for irregular work pieces. They initially activated the extra feature but set it to expire in a year. Really? My version of the machine at least also doesn't have limit switches and no way to add them with the included electronics that I can find unless I want to replace the control box electronics with an aftermarket solution-which would fix all of the problems with their proprietary approach.

The only reason I bought this one is that I got a great deal on it at a garage sale. The guy assembled it but never used it and sold it for about 1/3 the price of a new one. Which leads me to one more gripe. When I first got the machine, I had a little bit of a problem reaching them to activate the software and make the machine usable. Once I got someone to answer the phone the service was very good but it certainly felt to me like a small mom & pop operation which didn't leave me feeling good. Had I spent $4-5k for my setup, I would have been worried because without the activation you cannot use the machine. Even moving the software to another PC will require contacting them to reactivate software and all of the proprietary features. Not a good model.

If I were shopping for a new machine, I would look at other options.


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## Woodnmetal

Nick,

I will throw this out their, perhaps it will help with your decision. Hopefully, others with CNC woodworking experience could possibly add to this or correct the way I program my 4th axis in metal machining.

In my case, The 4th axis has its own post with an "A" value. The post adds in the A axis rotation. In that case, I pick up my X,Y,Z from the clamped work piece, which is in relationship to my machine home position. I usually pick up my cutter from the center of the chuck in Z if I have no tool changes. With tool changes I just add or post out an "H" offset value. In that case I add a G43 with the corresponding tool # in use. (G43 H2 Z..)
This may be a little different on the woodworking CNC machines…. Hopefully other members will correct me if Im wrong.

Having said the above,

Since the machine of choice will be your 1st CNC machine, I wouldn't try mixing and matching, editing posts etc.
If it were me, I would purchase the 4th axis along with the machine you choose. I say this because, you will have the software update, tech support, along with the post needed to generate the program with the A axis.

Hope this helps and others add their experiences!
Cheers,
Gary


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## Nicky

Good info from all. My career has been working with computers. I'm a fan of open source solutions. I would steer away from proprietary software because of costs and limitations. I like lazymans description of "artificial constraints".

Woodnmetal, I don't understand your second paragraph because I'm just getting started and trying to learn how the technology works. You have given me some principals that I need to learn about. I do enjoy the research process. I won't try mixing and matching and do understand the benefits of purchasing the manufactures supported options.

These Chinese machines are cheap, and many manufactures pumping them out. I'm not a commercial shop and looking mostly to play with the technology. I want to purchase a machine that can do inlays in small jewelry boxes. The 4th axis looks interesting.


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## Mike_D_S

As a thought exercise, in normal 3 axis the positioning is about placing the cutter relative to the work piece. In 4th axis think of placing the workpiece relative to the cutter.

Want to cut splines down a cylinder? its a 3 axis operation followed by a 4th axis then repeating the 3 axis cut. Lots of more complicated stuff like screw threads, etc but generally I find it helpful to think about it like above.

Be careful on the "upgrade with optional 4th axis kit" language and make sure you can actually order the kit. I notice on the Sainsmart site they sell the 4 axis electronics kit with the stepper, but I could not find a mounting hardware kit and other bits need to actually install it on a machine.

Since you have the PC background the software won't be an issue for you, but the concept of "open source" can get sketchy when talking about the electronics boards themselves. Not trying to talk you out of that particular machine and the general frame design seems reasonably robust, but if it doesn't work great out of the box be prepared to tinker and checking to see if this machine has an active user group you can engage with would be important to me if I was buying it.

You're not a production shop as you said, but spending $1000 on a machine which only works 50% of the time gets old too.

Mike


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## Nicky

Hi Mike,

I did contact Sainsmart about the 4th axis. They replied that it was not available, nor did they provide any software or support for a forth axis.

I think that I'm shelving the idea for now. Functional units are commercial grade and way more money for "playing around" then I want to spend.

I've not settled on a CNC yet. The 4030 is about the max size I'd use so I'm still doing some research. I have played around with Fusion 360 and this seems to work well for what I'm looking for. I would prefer an open source solution, but they need work to be usable.

I look forward to tinkering. At some point I will learn how to use the technology then it becomes another tool in my shop. Granted a tool with a larger learning curve, but I'm up for the challenge.


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## Lazyman

The right software goes a long way to lowering the learning curve, regardless of what machine. My machine came with VCarve which is actually pretty simple to learn to do the basics and made it pretty easy to jump in quickly. There are lots of tutorial on their website as well as YouTubers. A few machines come with their own software which may make it easy to use their machine but if you want to be able to upgrade to a better or bigger machine, portability is important.


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## LumberJockMan

Just as an option.. Have you considered a Mach based CNC.. Either Avid or one of the many DIY designs?
The advantage is that it's straight forward to add a 4th axis in Mach.
I used a lathe, I put a timing pully on the end of the headstock shaft, then another timing pully on a Nema 34 stepper, and of course, a timing belt between them. And obviously, the original lathe motor is no longer connected
It works pretty well.

Sometimes you want the piece on the rotary axis to be still while the router moves in X, Y, Z.
An example of this is the top of a table leg with a "cube" top. 
These are times when I disconnect the stepper and use the spindle lock (that they use for indexing on the lathe).
It makes it more stable. If you don't have an indexing wheel on the lathe, you can stuff shims between the bed and the blank on the rotary axis to give it a little bit more stabliity.
So why do this? I have found that when I cut a cube on the top of a table leg with Aspire, it rounds over the corners. It looks a lot better to lock the spindle, do a pocket cut, manually rotate 90 degrees .. repeat for all 4 sides.

Excluding the cost of the lathe (which I already had and can switch back to lathe mode), my costs were the stepper, another controller (Gecko 203V), timing belt/pulleys, and I paid $80 to get the hole on one of the pulleys enlarged to fit on my headstock spindle.. So the cost to do that today would be about 400-450 plus the lathe.
Not cheap, but I wanted to give you the information so you could make your own decision.


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## mpsprunger

C- axis is the forth axis, it would rotate the blank on the table mount


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## Mike_D_S

Wow, I hadn't look at kit prices for a while. At first I was thinking there should be several entry level hobby CNC kits for a grand, but not so much. Even an Xcarve or Bobs is well over that.

The best thing maybe to just watch CL and local listings. I lurked about 4 months and finally found a great deal on a upper end hobby level machine. The guy had bought it to be the new Etsy millionaire and 6 months later was selling it after giving up on making money at it. I paid about 50% of new price on a 3' x 5' machine.

Mike


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## Nicky

update

I gave up on a 4th axis (for now).

I bought the PROVerXL 4030. Put it together last night. Assembly directions were clear. The cnc looks well built. My only complaint thus far is the spoilboard flexes more then I'd like to see. This is an easy fix.

I will install the software this weekend and start playing. I've installed the free version of Fusion. I did not understand how powerful this software is for cad and cam.

-nick


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