[JeffsInventions]

I am interested in buying a milling machine and converting it into a CNC mill. I look forward to figuring out and executing the conversion as well as having a tool that I can use to make parts for a range of projects. I am interested in your input as to which brand and/or model of mill I should buy for the conversion.

These are some criteria that I have come up with (though I would be curious if you could argue why a criterion doesn't make sense or suggest other criteria that I'm missing)

• bench top (I would like to be able to move it with 2-3 people: I've seen some tempting Bridgeports on craigslist, but can't figure out a way to get them from the seller to my garage without paying a couple hundred dollars to rent a flat bed truck--not to mention incurring a big expense any time that I move in the future)
• capable of doing metal working: anything from aluminum to stainless steel
• 110v single phase (I would like to use it in the house I live in and potentially in future houses without having to re-do the wiring)
• 3-4' wide table (I don't want to find myself in a situation where I want to make a part bigger than my mill can bear)
• naturally, great build quality (I would like to use the mill to make relatively high precision parts for the rest of my life).

Now for some features that I would love to have. Admittedly, I would be shocked if I could find a machine that has them that does not cost a fortune. Though, it would be nice to pick up a mill that wouldn't make it a nightmare to add them.

• 5 axis
• self-changing tooling

I would be up for paying up to $2000, but would prefer to be in the $750-1250 range.

What machine do you suggest that I buy?

[jid2]

If you have room for a Bridgeport - there is your answer. If you look honestly at the cost of having machining, especially CNC in your garage, paying a couple hundred bucks for a rigger to deliver the machine is nothing.

If I had the space for a knee-mill I would have started by buying a 3 Axis CNC bridgeport or something. You can score those for $5-7K easily and you are ready to run.

But I don't have the space, so I'm spending more money and investing over a year of my free-time to do a conversion. Add up all the cost and time to get what you want. The investment in the mill itself is pretty small for the typical conversion. Especially when thinking high-precision, large table, stainless..... What's your total budget and timeline.

[jeremy0203]

good luck finding something for that price that fits what you are looking for.

I am interested in buying a milling machine and converting it into a CNC mill. I look forward to figuring out and executing the conversion as well as having a tool that I can use to make parts for a range of projects. I am interested in your input as to which brand and/or model of mill I should buy for the conversion.

These are some criteria that I have come up with (though I would be curious if you could argue why a criterion doesn't make sense or suggest other criteria that I'm missing)

• bench top (I would like to be able to move it with 2-3 people: I've seen some tempting Bridgeports on craigslist, but can't figure out a way to get them from the seller to my garage without paying a couple hundred dollars to rent a flat bed truck--not to mention incurring a big expense any time that I move in the future)
• capable of doing metal working: anything from aluminum to stainless steel
• 110v single phase (I would like to use it in the house I live in and potentially in future houses without having to re-do the wiring)
• 3-4' wide table (I don't want to find myself in a situation where I want to make a part bigger than my mill can bear)
• naturally, great build quality (I would like to use the mill to make relatively high precision parts for the rest of my life).

Now for some features that I would love to have. Admittedly, I would be shocked if I could find a machine that has them that does not cost a fortune. Though, it would be nice to pick up a mill that wouldn't make it a nightmare to add them.

• 5 axis
• self-changing tooling

I would be up for paying up to $2000, but would prefer to be in the $750-1250 range.

What machine do you suggest that I buy?

[kensbey]

Unfortunately, i am going to have to agree with the comments so far. I feel your criteria are in conflict a little.

Most prominantly the bit about moving with two or three people. That pretty much limits you to X3 sized machines or smaller, and these are slow work with mild steel, let alone stainless. I'm sure it can be done, but you will be taking tiny cuts and lots of time. Not to mention column flex etc, in these smaller machines.

For that price, i would reccomend a rf-45 style machine if you want benchtop. but as jid2 said, if you have the space, get a knee mill. you won't regret it.
While we're talking about cost, remember that the cost of the mill is only a fraction of the cost of the project. for example, in the way of tooling, you will need:

Vise: $200-$300
Parallels: $50-100
collet set: $150-250
cutters: $50-$300
Dial indicators: $200
calipers: $100.

And thats before you even start the conversion!
An x3 will take about $1500 for ballscrews, steppers, and electronics (minimum), you can double that for an rf-45 size machine.

Now obviously all these costs will vary, but i'm just trying to point out that saving a few hundred dollars on the initial cost of the machine may not be that important in the long run. you don't want to get to the end of a 6 month project and wish you had started with something better.

Sorry for being so negative, just trying to put things in perspective

[JeffsInventions]

Thanks for all of your comments.

I have a friend who will sell me a Bridgeport J from the 60's in the $1500-2000 range. I would pick it up and then do a conversion something like the one here: Converting a Bridgeport to CNC.

However, I've read some concerns about using a manual bridgeport as a starting place for CNC conversion:

• To Convert old Bridgeport to CNC or not ? - The Home Shop Machinist & Machinist's Workshop Magazine's BBS
• http://www.cnczone.com/forums/bridge...onversion.html

What do you think? Are their arguments against this approach valid? Should I go for it and do the conversion or try to look around for a mill that already has controls (even if they are broken) and start from there?

[SCzEngrgGroup]

I have a Chi-wanese Bridgeport clone I bought for $3750 brand new a few years ago. It is now fully 3-axis CNC, using Nook XPR ballscrews with double nuts, and DC servos, and I now have over $10K "invested" in it. It's a great machine, but has its drawbacks. Probably the biggest is that a knee mill is near impossible to fully enclose, and if you're doing a lot of work, and want to get it done fast, you really do need flood coolant on a machine this size. Mine is fast (350 IPM rapids on all but the knee), accurate (generally good to about a thou or so - which is as good as it gets on a hobby machine), and reasonably reliable.

Now, would I do it all over again if I were starting now? No. The size of the machine is very handy - I've had jobs where I used every inch of its 34" x 14" x 16" work envelope, but I could've got by with less, and on most jobs much less. It would've been nice to have a fully-enclosed machine, to contain the mess better. Were I to do it over today, I'd consider a used VMC, a Tormach, or a Mikini. They would be better suited to real production work, and would have cost about the same. Instead of spending several years off and on doing the conversion, and the constant upgrades and enhancements, I could've been doing real, paying work, and come out money ahead.

IMHO, if you scrimp on the cost of the machine, it'll end up costing you more in the long run. Unless you're doing it purely for entertainment, with no solid goal in mind, figure out what you need to do, then bite the bullet and spend the money to get a machine that gets you doing that ASAP. It's nice to spend time doing real work WITH the machine, instead of spending all your time working on the machine.

Regards,
Ray L.

[asuratman]

Hi JeffsInventions,
If you one to have cnc mill low cost,you should DIY cnc mill like mine here. Everything are available and easy to get. For 3 axis, just bought 3 ballscrew, some plate, electronics. For 5 axis, its expensive, you need precision.

[JeffsInventions]

After reading the replies and doing some more research on my own, I think I'm going to go with a US version of the BF-20, the Grizzly G0704. Here is why I didn’t choose the other form factors.

• Mini-mills are not heavy duty enough and would take too long to cut hard metals.
• RF-45′s and Bridgeports are too heavy to move and too expensive, in time and money, to convert.
• VMC’s are too expensive.

Looking around on line, I think I am aiming to do the G0704 CNC conversion for under $2000 + the $1000 machine = about $3000. Is this a reasonable estimate?

Besides waiting for a back-ordered machine to come in, are there other downsides to this approach that I am not considering?

[hoss2006]

Very reasonable estimate, I've a cost rundown for a DIY version here, you can spend a bit more (about $4-500) for premade mounts from ebay billy or cncfusion if you want to save a little time.
http://www.g0704.com/Shop_Info.html#costs
Hoss