[Bradyz]

I own a very small downhill skateboarding business and I have been looking for a couple of cnc machines for the shop (a metal cnc and a wood router). I currently have all of our jobs done somewhere else and I was wondering if it was possible and if it would be worth it to buy my own cnc and make the products from my own shop. All of our parts are made from 6061 or 7075 aluminum (all smaller than 3"x8"x1" or 3"x4"x3"). We make about 200 parts a month.
I recently saw locally someone selling a Grizzly g0463 with a Promica cnc conversion and custom coolant table for about $2000 and I was wondering if it would be capable of the job.
I have some experience with writing Gcode, working in CAD and working on mills and lathes but I am still very inexperienced when it comes to cncs. I have been looking at getting Mach 3 and MeshCAM to go with the Solidworks and Rhino software I currently use. I also hope to build my own Joe's cnc so having a metal cnc would help out a lot. Any advice is very much appreciated. Thanks.

[fizzissist]

Buying a toy to make toys might not be the best business decision.

[Bradyz]

Buying a toy to make toys might not be the best business decision.

Thank you for elaborating.

[wizard]

I own a very small downhill skateboarding business and I have been looking for a couple of cnc machines for the shop (a metal cnc and a wood router). I currently have all of our jobs done somewhere else and I was wondering if it was possible and if it would be worth it to buy my own cnc and make the products from my own shop. All of our parts are made from 6061 or 7075 aluminum (all smaller than 3"x8"x1" or 3"x4"x3"). We make about 200 parts a month.

It probably depends upon where you can put the most value. I wouldn't jump into both the router and mill at the same time. My guess is that a router would be the first step to take.

I recently saw locally someone selling a Grizzly g0463 with a Promica cnc conversion and custom coolant table for about $2000 and I was wondering if it would be capable of the job.

We don't know what the job is. I can imagine what the skate boards would look like but there is almost infinite variation in the trucks.

I have some experience with writing Gcode, working in CAD and working on mills and lathes but I am still very inexperienced when it comes to cncs. I have been looking at getting Mach 3 and MeshCAM to go with the Solidworks and Rhino software I currently use. I also hope to build my own Joe's cnc so having a metal cnc would help out a lot. Any advice is very much appreciated. Thanks.

I wouldn't go that route and instead would implement a moving table machine. Made fairly rigid it might be able to also handle your aluminum work. You are right in one sense building a machine like a router requires a bit of machinery unless you buy a complete kit or fully assembled machine. Note that I say might because I don't know if the geometry and tolerances on your aluminum parts are conducive to machining on a router type machine.

[wizard]

Thank you for elaborating.

He has a point, if you are going to DIY machinery for production use you don't want to do it half assed. I have no problems with "home" built machines, some times it is the right thing to do, just make sure it robust enough.

Beyond that if this is your first machine build, you will be on an extended learning curve. Many companies learn to leave machine tool building to machine tool builders. It really depends upon how much free time you have to invest in the build.

[Bradyz]

He has a point, if you are going to DIY machinery for production use you don't want to do it half assed. I have no problems with "home" built machines, some times it is the right thing to do, just make sure it robust enough.

Beyond that if this is your first machine build, you will be on an extended learning curve. Many companies learn to leave machine tool building to machine tool builders. It really depends upon how much free time you have to invest in the build.

Thanks for the help Wizard. I am still pretty new to machining and don't really know the differences in a very high end machine vs something much smaller. The x3 machine that is for sale is already assembled so it is ready to run. The router isn't a huge priority and will be a project that I am working on for the next few months (right now we can do everything by hand in the shop it would just be nice to save some time and have all of our boards cut with a router).

This is a picture of the most complex thing we are currently making. The thing that I would most like to have machined in the shop is the long part with the rod through it. We would probably have the hole where the rod is pressed through done at another shop if we couldn't do that ourselves.
I would love to be able to just make one cnc machine that has a cutting area big enough to cut out our boards and rigid enough to cut our trucks from aluminum. I feel like it would be really simple and cost/time effective to just lay down a sheet of aluminum on a 4x4 router and cut out 100 peices at a time but I haven't been able to find a build that would be that rigid. Any thoughts?

[Scott_Tool]

you should be able to do a press fit in house with the proper reamer but my recommendation would be to get a nice mill, have that part cast and then just clean, pocket and drill it in house, if you wanted to go a step further build or buy your own die casting machine and do it all in house. Now if you want to make a real investment get a multi-axis machine and run the whole part in one operation but they are pricey.

[wizard]

It is interesting that you want to machine the metal pieces first instead of going the wood router and the metallic machining. With no experience I would think it would be easier to ramp up wood machining on a router type machine. If you are starting out with zero experience I think you are going after a challenging metallic part.

As it appears in that rendering I don't see this item being easy to do on a 3 axis machine. Plus you would need to have the hole for the shaft bored some how. In fact I'd be tempted to bore and press in the shaft before machining the hub / axel support or what ever you call it. I'd also avoid cutting all the way through to reveal the pressed in axel.

Personally, as rendered, I don't see this as a practical part for an X3 sized mill but that is me. Depending upon which avenue you take you could be looking at a commercial mill in the $12,000 to $40,000 range. That just to profile the part and bore the pivot.

The responder above mentioned die casting, an industry I spent several years of my life in. That was zinc die cast which is slightly different than aluminum, in any event long term this might be a better path to follow if you expect volumes to ramp up. However even if volumes ramp you wouldn't want to die cast in house. The thing with a die casting is that you could then set up small mills to do a reaming operation for the pivot and a drill or boring operation to clean up for the pressed in shaft. You might not need CNC for that. The problem is die casting the part requires investment in a mold which you own. Since my die casting days where maybe 25 years ago I wouldn't want to even guess the cost of the die/mold. However get with the right supplier they should be able to estimate the cost closely and tell you how much the part will cost each. (Cost is roughly based on the weight of the metal). Plus a fixed setup charge, which can be huge when dealing with low volume parts. You would probably have to sell a lot of parts to pay for the mold, but I can't imagine you are getting each CNC machined axel assembly cheap these days. One other gotcha with die casting is trimming the part.

I could be wrong but I'm assuming you are paying a high price for the part and thus are looking to do it in house to lower costs. That is all well and good but it is often better to put capital else where. Buying a CNC machine will not give you an instant solution.

[Scott_Tool]

Ah, I just realized I left something out of my post, I meant to say get a nice mill so you can make your own die mold.

[Bradyz]

It is interesting that you want to machine the metal pieces first instead of going the wood router and the metallic machining. With no experience I would think it would be easier to ramp up wood machining on a router type machine. If you are starting out with zero experience I think you are going after a challenging metallic part.

As it appears in that rendering I don't see this item being easy to do on a 3 axis machine. Plus you would need to have the hole for the shaft bored some how. In fact I'd be tempted to bore and press in the shaft before machining the hub / axel support or what ever you call it. I'd also avoid cutting all the way through to reveal the pressed in axel.

Personally, as rendered, I don't see this as a practical part for an X3 sized mill but that is me. Depending upon which avenue you take you could be looking at a commercial mill in the $12,000 to $40,000 range. That just to profile the part and bore the pivot.

The responder above mentioned die casting, an industry I spent several years of my life in. That was zinc die cast which is slightly different than aluminum, in any event long term this might be a better path to follow if you expect volumes to ramp up. However even if volumes ramp you wouldn't want to die cast in house. The thing with a die casting is that you could then set up small mills to do a reaming operation for the pivot and a drill or boring operation to clean up for the pressed in shaft. You might not need CNC for that. The problem is die casting the part requires investment in a mold which you own. Since my die casting days where maybe 25 years ago I wouldn't want to even guess the cost of the die/mold. However get with the right supplier they should be able to estimate the cost closely and tell you how much the part will cost each. (Cost is roughly based on the weight of the metal). Plus a fixed setup charge, which can be huge when dealing with low volume parts. You would probably have to sell a lot of parts to pay for the mold, but I can't imagine you are getting each CNC machined axel assembly cheap these days. One other gotcha with die casting is trimming the part.

I could be wrong but I'm assuming you are paying a high price for the part and thus are looking to do it in house to lower costs. That is all well and good but it is often better to put capital else where. Buying a CNC machine will not give you an instant solution.

Die Casting is something that we plan on doing in the future but like was mentioned the cost for getting a die made can be a huge investment and we still make a lot of changes every so often to parts.
The part probably looks a lot more difficult than it is. All of the radiused edges are done with a single radius bit. Drilling the hole seems like it would be the hardest part to do but shouldn't be too difficult if we make the right fixtures for it. Right now the parts are made on a 3 axis machine.
Someone I know will be selling a bridgeport torqcut 22 cnc for under $10,000 I might just wait for that.

[DSpeck]

Rather than die casting this part, you could have it lost-wax cast. Have an aluminum mold made for making the waxes, and then give the molded waxes to your molding company for sprueing and putting on a tree.

From the sizes you quote in the first post, they could likely do them 10 at a time, and with excellent detail. That would leave only the long hole to be drilled/reamed, which can be done on any 3-axis mill with a sufficient Z-axis clearance. You would likely have to pay for a set of softjaws, but that would be a one-time charge. You might be able to do the holes yourselves, on a manual mill (RF-45 maybe?), instead of sending it out.

Just some ideas for you, YMMV.

Doug.