[Simplex78]

I am a newbie that has been lurking for about a month, and must confess that I am overwhelmed at the moment as to how to proceed, so maybe you can give me some recommendations.

I am looking towards building a wood router set-up for fabricating structural wood for antique vehicles. I own an antique automobile restoration shop in which we have a full woodshop in-house where we make structural pieces for the infrastructure of the vehicles we are restoring. I have included pictures of several pieces below that shows assemblies of individual pieces. Presently we have many patterns and samples, along with factory prints to work from, -and are slowing digitizing them thru SolidWorks. Because of this, I am looking to fabricate a unit where we can test the waters to see if there will be any savings to my customer(s) over handcrafting & fitting each piece to the body.

Most of the pieces we deal with are less than 12" in width, -and the majority are less than 5 inches in width. We do deal with some pieces that around 70+ inches in length however the majority are 48 inches in length or less. If on the rare occasion we do need to deal with a piece longer than the table length, we could improvise by using pegs to index off of to reposition the work piece. For the most part, we use 4/4, 8/4. and sometimes even 12/4s Ash, and the biggest reason for us using a CNC unit would be to cut each wood component to the proper shape, and we will still hand-fit as needed. While speed is somewhat important to us, breaking the "budget bank" to obtain furniture-grade quality at production speeds is unnecessary for our application. My budget is such that I cannot justify spending $8-$10 on a RTA kit, and I really need to hit somewhere around $4k for build materials to make this a justifiable project.

I am thinking I would like to build an 8" thick Torsion Box table using MDF with an internal grid for the strength. From there I am struggling on what to use for linear rails. Also, do I/we want to use ballscrews or R&P for drives, --and should I purchase NEMA34 or 23 motors? I am open to using 8020 material to fabricate the Gantry, -or I am open to constructing it from other materials. I probably would purchase a commercially constructed Z-axis of someone's recommendation. Additionally, is a 2.2kw Spindle with the larger collet size the direction I should be looking at? If so, any specific recommendations for this purchase along with other components such as Breakout Board, Stepper Mtr. size, etc.? We presently have a small entry-level 2'x2' CNC Plasma that uses Mach3, so I would probably purchase this to operate this unit.

I believe the last piece of information I need to give is the anticipated 'duty cycle'. Most car bodies we restore will use anywhere from 25-40 pieces that when assembled would makeup the complete infrastructure. Presently we average about one body per month in fabricating and installing the wooden infrastructure. I have no idea what speeds or how many inches each piece will/should take, but if we used the high average of 40 pieces to fabricate as a baseline, and each component of the assembly averaged an hour each including set-up time, etc., I can see an average of 30 hours of sporadic run-time of the unit per month for each project. Hopefully this gives enough information to help spec out what I need to be searching for.

Thanks in advance for any assistance or advise you give.
Brent

[milo30]

Have you shopped around for used machines or possibly a Chinese machine? Building a machine for hobby use is one thing but if I had a business, I would rather not have to spend my time building, especially if I was a newbie. I just purchased a new Chinese machine last weekend and it was 4'X8' with a 4HP spindle for $6200 ( I paid an extra $600 and picked up the rotary axis also) and it came with a dust collector. You don't need a machine that size so you would probably get it already assembled and running around your budget. I found a US dealer that brings them in and makes sure that they are running right so I didn't have to deal with importing.

If you want to build your own maybe you should look at Finelineautomation Saturn series.

[wizard]

I honestly don’t think anybody could spec out a machine for you with any confidence. Mainly because there are so many options and ways of building such a machine.

I’m going to assume that you have a reasonable wood shop here so a wood framed machine is a real possibility. I wouldn’t go MDF though as I really hate the stuff. Instead consider birch ply or newer materials like bamboo. Design with an eye towards stiffness and even the gantry will be fine.

However you apparently also have some metal working capability in the shop. If so I’d consider steel for some of the machine. How much depends upon what you have tooling wise and what you can get done locally. Steel is a good option for significant parts of a machine. For example the gantry beam is short so a beam of suitable length might be found in the drops section of your local steel supplier for around a dollar a pound.

You mentioned hand fitting but do realize that a decent CNC machine should produce very accurate parts. Done right a CNC should greatly reduce hand fitting. If you are going to bother with building a machine make sure it is good enough for the job.

As someone else mentioned sometimes your best bet for a low cost solution is finding a used machine. Even if it has a clapped out controller or mechanical problems you will likely save time and money overall. Since this is a business anything you build or rebuild will need to meet all current safetry standards. I’m not a big fan of buying from China but you have a variety of machines to choose from of varying quality.

[Simplex78]

Thank you both for your excellent responses. Yes Wizard, I do have a decently equipped wood shop, -and I also have an in-house machine shop along with a metal fabrication shop however the biggest 'fear" I have endured throughout this planning stage is what to do about electronics. I am naïve about which brand of stepper motors to use or sizes, along with which controllers, --where to purchase them, and other such items such as Z axis' and gantries. In may instances, I think I would rather purchase a commercially available Z-axis or even a Gantry if they fit within the budget. Milo, thank you for the heads-up on Finelineautomation. Are there other reputable sources for components I should be considering??

[he1957]

Hummm,

Great question and nice pieces (which could easily be made by CNC).

With a budget of some $4.0k and a request such as this, ask yourself how much do you cost/charge yourself at an hourly rate, per day; over at least two years (warranty - but not on a DIY machine) plus holidays, sick leave, insurance, depreciation and other stuff?

Get what you pay for. You will likely need an accurate touch probe (with machine to drive it) to profile "old" parts to replicate (and software to fill in for the rotted timbers) - good ones are not inexpensive.

Use this to get a handle on what you are really asking.

Hummm...

[MARV]

Brent,
Normally I wouldn't weigh in on most subjects here, but I come from a production woodworking background with nearly 50 years experience in the trade and have managed to transition into CNC work. I think I know a bit about what I speak. I also know that wading into something like this can burn an inordinate amount of skilled man-hours. The first question I would ask; do you get paid to diddle around with machines or do you earn your keep by turning out product at the end of the day? If you pursue a DIY partially built from scratch CNC, your pay back will be questionable and the end result may be a big disappointment.

My suggestion is to take a hard look at what you expect to get from your CNC; are there unusual joints to be cut, how exacting do your parts need to be, what will be the parts count at each run, is surface quality important, etc, etc. Will 3 axis capability be enough after you're a year into this?

I am currently into my second build (I'm currently retired and have the time to spend) and it is a handful (control built from scratch, different motors, etc.). As a point of reference, my first build (for my last employer) was adapting a 6 axis ABB robot to CNC carving work (also a mind bender). My point here is buy from well known sources with proven product. Folks on this forum will have a lot of recommendations and will offer great support. But I think you would be well advised to look for a complete system. Could be a kit, but do your due diligence. The fact that you are already mapping parts in Solidworks suggests you are committed to doing this right to begin with. At the end of the day you want to mill parts successfully, not burn time and money.

By the way, the kit that I started with and would highly recommend came from CNC Router Parts. A Pro Series unit. They were very helpful, and modifying a standard unit won't break the bank. It may be a bit over your stated budget, but like they say "you get what you pay for". Hope this helps.

Marv

[Simplex78]

Hey Marv, thank you for the insight and advice. Yes, you are correct that our job is to produce saleable products at the end of the day, ...HOWEVER sometimes we must fabricate tools, jigs, and fixtures that are suited more for our needs instead of the typical consumer. Our (English) Wheeling machine and our pneumatic Planishing Hammer are prime example of tools fabricated to meet our needs which were not commercially available instead of purchasing a generic size. The same applies to wood shop tools, ...and I think this tool is likely to fit into that category. (-note the odd dimensioned table)

To answer specifically regarding what I am expecting, there are some unusual compound curves that will need to fabricated, and these parts probably have a 0.010" tolerance available. The parts count would likely be one piece for each vehicle's application manufactured at a time. From a long-range expectation, I want to visually see the costs savings (-if any) using CNC over custom-fit applications, -and if we find the ROI is worth the investment of a commercially available unit, then we will proceed in that direction. The other hidden advantage for me is my wood shop craftsman has been with me for over 12 years and is likely to retire within the next couple of years. Having the ability to digitize and produce items in his absence eases the pain of hiring & training a successor.

Your last paragraph has great merit, and I am one that firmly believes in that however what I am naïve about, is whether purchasing a 'kit' from the company you mentioned is the proper way for me. When I priced a PRO kit' from their website, their costs were substantially greater than others. Since we have used 8020 materials in-house, it appears there is a large mark-up on those materials over my costs by that company. Naturally Drew needs to eat and make a profit, however it would appear that I am purchasing items that he is purchasing, modifying to his specifications, and then selling those items to his customer. While there is not a problem with that method whatsoever, it would appear that I would be paying a premium for he or his employees to do the same thing I have the capability to do in-house. Maybe I am incorrect in this assessment, ...and if so I would definitely like to hear the experience of others as to which items they purchased and where they purchased them from. Thanks again for your thoughts!!

[ger21]

however it would appear that I am purchasing items that he is purchasing, modifying to his specifications, and then selling those items to his customer. While there is not a problem with that method whatsoever, it would appear that I would be paying a premium for he or his employees to do the same thing I have the capability to do in-house. Maybe I am incorrect in this assessment

You're paying for the hundreds of hours of R&D that they've spent over the years, and perhaps more important, the ability to call them for help when you have a problem, or even a basic question. They support their products, and support costs a lot of money.
I don't thinks there's a lot of savings in the mechanical components. Where you can save a fair amount, is in the spindle, and electronics. But if your time is worth $$, that savings will go out the window. It can easily take 50 or more hours to design and assemble all of the electronics.

[adam_m]

Lots of smart guys on this forum that have numerous years in fabricating and using CNC's.

I'm a hobbyist and can tell you that even though you could get away with a torsion box type setup I would build something more substantial or purchase a used machine. Even though a wood based machine can and will perform up to a degree when you start talking about making a living from your machine you'll be better served investing for the future instead of having to re-invest to upgrade your machine at a later time due to lack of performance from your machine.

CNCRouter parts sells some kits for the amount of money you're looking to invest and I would suggest you buy a kit unless you have time to invest in building, time costs money. If you're working on your machine you're not doing something else.

From the pictures you provided, a CNC would be a great addition to your business.

Just my 2 cents.

Adam,

[coherent]

I think the majority of folks who build their own CNC machines do so because the building is a big (biggest in some cases) part of the CNC experience for them. If that is why you are proposing to build one, then feel free to ignore the rest of my post. Sure you can save a few bucks, but in the long run the endless hours you put into it doesn't come close to making it a worthwhile proposition based only on saving money. There are a number of dealers that sell quality kits or components that when push comes to shove, are close to your cost anyway. Take a look a some of the following online sites as an example...
CnCRouterParts
FinelineAutomation
CNC4PC
AutomationTechnologiesInc

I personally have build a few machines for both routers/spindles and for plasma. I have also bought complete kits or machines including Torchmate and a Saturn model from Fineline. The Saturn in my opinion was by far the most solid and rigid machine for router/spindle use for the price I could find. I wouldn't hesitate to use it for production of parts like you are building. The ability to add your own electronics to a nearly complete machine offers a fairly quick means to be up running, but still allows you to save by sourcing your electronics to suit your needs and building the base (be it wood or metal) to your specs. Building from scratch can be a fun project, but when it comes to sourcing linear rails, screws, ballnuts, bearings, stepper mounts, etc, etc it's not a couple weeks project. If you are a proficient welder, have a metal shop with a mill and lathe etc then you'll at least have some of the tools necessary to do it right. I personally wouldn't want the main frame of a router I was going to use for even limited production work to be made out of wood. Can it de done? Sure, but I honestly think it will cost more in the end and not perform as well. Weight, side forces, precision and wear and tear become issues that are simply better suited for metal. A nema 23 setup with a VFD and spindle will cut wood all day long and simplify your part production tremendously. If you're new to CNC and want to use the machine for making money, you'd be much better off learning the software side (cad, cam etc) of things (which can be quite a learning curve) than designing, engineering and building of a machine. The ability to pick up the phone when you have a question or an issue and get some support and stay up and running is priceless.

[wizard]

H
Your last paragraph has great merit, and I am one that firmly believes in that however what I am naïve about, is whether purchasing a 'kit' from the company you mentioned is the proper way for me. When I priced a PRO kit' from their website, their costs were substantially greater than others. Since we have used 8020 materials in-house, it appears there is a large mark-up on those materials over my costs by that company. Naturally Drew needs to eat and make a profit, however it would appear that I am purchasing items that he is purchasing, modifying to his specifications, and then selling those items to his customer. While there is not a problem with that method whatsoever, it would appear that I would be paying a premium for he or his employees to do the same thing I have the capability to do in-house. Maybe I am incorrect in this assessment, ...and if so I would definitely like to hear the experience of others as to which items they purchased and where they purchased them from. Thanks again for your thoughts!!

I'd like to comment a bit on this subject of aluminum extrusions and CNC builds. I know this flies in the face fo what is a common approach in these forums but I don't like Aluminum T-Slot extrusions for use in a machines main structure. The materials are expensive, especially if you go with the heavy weight stuff. Part of that expense comes from the way you are nickled and dimed for fasteners and other accessory parts. The only case where kits or extrusion builds make sense to me is when someone want a machine and has little in the way of equipment to build the machine.

As for the markups well if you order 8020 custom cut, from one of their distributors, you will be paying for that service. The reality is the extrusions are not cheap to start with so processing charges just make the cost impact a bit worse. So I really can't knock somebody for reasonable charges associated with building a kit, you can't expect them to do it for free. However if you are trying to control costs and have the facilities available to fabricate, avoiding kits can make lots of sense and cents. The more you DIY the build the greater your ability to build a more robust frame and other components.

One thing to consider here is that your production estimates indicate extremely low machine usage. Hobbyists can actually be seen using their machines more intensely. You may be underestimating the usage but if accurate you don't need a massive machine. IF you have underestimated or end up finding many other sues for the machine, you could easily under build the machine. I'd lean to a far more robust build and strive to use the machine as much as possible.

[MARV]

Brent,
As I mentioned earlier, a lot of good advice on this forum. The challenge is to ferret out what might apply to your application, something only you can determine. So I thought I’d describe the rational for the choices I made buying my machine with the thought there might be some insights gained.

At the outset, I new that I might have this device for perhaps the next 5 or 6 years (I’m retired and 70 years young). And I wanted a fairly flexible format so that the next owner would have options to tailor the device to his or her specific needs. That meant a bolt together machine frame. Also, access to my space is very confined, so I bought the CNC Router Parts Pro 2 x 4 (gantry length running the long dimension). This machine can be modified down the road to do 4 x 8 panel work (and possibly larger) with the simple addition of longer extrusions and other hardware.

Ridigity required in a machine frame will always be a question of degree. Are you going to be doing aerospace parts? Me either. The first machine I spec’d and ran was an 11,000# Anderson with a 15 HP spindle. Very rigid. The second was a 4,500# robot fitted with an 8 HP spindle. Both could take a 3/8” x 1” pass in hardwood at 250” a minute. And accuracy was within the acceptable range of any fussy woodworker I know. That rate of stock removal won’t happen with any of the machines we’re talking about here. You’ll have to adjust accordingly.

I expect to be milling primarily hardwood with the possibility of doing some work in aluminum. It won’t have the capacity regarding stock removal that an industrial router would have, but knowing that going in meant that I will need to slow things down a bit and take smaller bites. I elected to buy a 2.2 kw spindle and VFD that will handle the chair parts that will make up the bulk of this router’s diet. If you have practical shop experience (as I suspect you have), you already have a leg up with regard to programming feeds and speeds and can manage this.

Knowing the constraints a 3 axis machine will have, I expect to add a 4th axis to do indexed (and hopefully simultaneous) rotary milling. And because of the need to mill tenons on ends of relatively short parts, I’ve configured my machine to allow gantry travel beyond one side where a drop down table will be fitted for mounting those parts (see the image of my configuration). The drop down will also allow for angular mounting of parts (with some adjustments in my cam software). With a spoil board mounted above the machine rails, I’ll be able to reposition parts to accommodate oversized stock. All possible with some inexpensive modifications to this baseline stock offering from CNCRP.

Where the challenge arose for me was the drive motors. I’ve had prior experience with CNC’d parts milled on stepper driven machines. These were high value parts, often a total of one in the run, where missed steps along one axis meant the part was trashed (or badly damaged). I expect to be doing a limited amount of work for a mandolin maker where material cost per board foot can be very high. Damaged parts as a result of a machine miscue will be unacceptable. I’ve elected to go with servo drives to (hopfully) circumvent this. Most, if not all, hobby/light commercial CNC routers use steppers. The controls offered with those machines are usually well sorted and relatively inexpensive. Because of the direction I’ve taken, I can’t ues the control or drives offered by CNCRP (or others) and will need to assemble my own. I should stress, I am not an electrical engineer. There are people on the forum who have detailed a path forward in this area, but it is something I am not looking forward to doing. I simply want to make high value parts.

Regarding the expense of this whole endeavor; my machine was not cheap by comparison (this is coming out of my retirement after all). However, the value of sourcing from CNCRP shouldn't be under estimated. I downloaded files for the stock machine frame, the motor spindle and Z axis from their website and modeled my machine in Rhino. I’ll be buying additional parts from them as needed going forward. And there was a bit of discussion with the folks there long before I spent a dime. They will continue to be a resource (I’m simply a customer with no affilliation).

I came up thru the ranks when there wasn’t much info on woodworking out there and CNC work was black magic. Sometimes learning was just plain hard. People shouldn’t have to struggle to do this as it can be tremendously satisfying. So, hopefully this discussion will help.

Attachment 406712