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Futaba-RC . A Main Hobbies . Boca Bearings

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CAD - Engineering - Technical > What's the cheapest you can get a VMC for?
 
 
sp1nm0nkey
Senior Heliman
Location: Redwood City, CA

I've got some ideas for some parts for my helis, and there are other things I'm thinking of machining, so I'd really like to try and find a used VMC somewhere. I don't mind rebuilding and cleaning and what not, but it'd be nice if it'd hold tolerances. So... what's the cheapest I might be able to find a haas, fadal, mazak, etc. 3-axis VMC for? Would it be cheaper to find a bridgeport boss and retrofit it with new servos?

Thanks,
Evan
04-29-2006 Over year old.
 
 
TMoore
rrProfessor
Location: Cookeville, TN

This is an open ended question. What do you really need to do? What kind of material, what spindle speeds, what type of spindle taper do you want? Are the parts carbon graphite, do you want the machine to be enclosed?

TM
04-30-2006 Over year old.
HOMEPAGE  
 
 
sp1nm0nkey
Senior Heliman
Location: Redwood City, CA

75% aluminum, 10% carbon graphite, 10% circuit boards, 5% steel/titanium. I'd like it to be pretty accurate, within 0.0005 at least. I might do a bit of turbine work, but it'll mostly be for helicopter parts and molds and such. I might be doing a few aluminum yo-yos here or there, see (http://www.dif-e-yo.com/). I know those are better suited to a lathe, but I figured I could get by with a mill, the guy on that site does, and I really like his work.

Most of all though, I'd like to learn how a full sized CNC machine works.

I'd rather not go with a taig or sherline, I have a taig lathe, and it's pretty puny. I'd like something that weighs around a ton or so. Something that can hack away at aluminum and sound like it's supposed to be cutting aluminum. A friend of mine does all his work on a bridgeport and a hardinge, and my heart broke after I saw him turn the entire profile for what would be his try at a yo-yo with a form tool, since it would've taken me hours. I'm also not a fan of the harbor freight/grizzley stuff, and I'd really rather not retro one of their mills.

As for tooling, I'd prefer R8 collets, but I don't have anything yet, so I'm pretty open.

And as for it being enclosed... sure, it'd be nice to keep the mess inside, and CNCs are always more fun to watch through a window.


EDIT: Just saw your gallery, and that tabletop unit looks really neat. How do you like it? Doesn't look like it meets the 1 ton requirement, but still, looks pretty neat.
04-30-2006 Over year old.
 
 
TMoore
rrProfessor
Location: Cookeville, TN

The price you pay will be solely dependent on the year of manufacturer and the condition of th equipment. Just be aware that industrial equipment isn't like building your own 2 or 3 axis motion contoller type cnc with simple spindle electronics. What this means is that the cost to repair real machine tools is significant. As an example, a Z axis encoder for my my table top mill went belly up after a few hours of run time. The retail price for the encoder was $300.00, my cost was a little less because we are dealers. It took me about 4 hours to replace it due to the way that it was installed and because I had to repair the pinblock that connected the motor and encoder to the amplifier. Since I used to be a service tech, this work wasn't unfamiliar to me but for the average person, you call a tech. It's these times where the money can rack up.

Whatever machine you buy, make sure it is under power, has all the manuals and that you see it run to it's full extent first before you buy it. There is a lot of junk out there so be aware.

TM
04-30-2006 Over year old.
HOMEPAGE  
 
 
sp1nm0nkey
Senior Heliman
Location: Redwood City, CA

What does that machine retail for? I'm starting to think that a full size VMC would be too much for my purposes, and a shrinked VMC would be pretty nice. Something in between a full size and a sherline/taig.
05-01-2006 Over year old.
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

The machine isn't the biggest cost. If your just starting and don't have years of machinist experience you can plan on spending a bunch of money on tooling. I'd say you could get a smallish 3 axis for $3000 - $10,000. Unless you get the toolholders in a pachage deal plan on spending another $800 on holders, and probably another $500 on workholding stuff (vice). Then you need to cut the material. You'd probably want at least a couple hundred for cutting tools if your running cheap, if you want a facemill and other nice to have items instead of just using a fly cutter your looking at another $1000 for a bunch of various cutters. Then don't forget you'll need 3 phase for most of the real toys, including the smaller vmc's unless you go table top size.
05-01-2006 Over year old.
HOMEPAGE  
 
 
sbalder
Senior Heliman
Location: Westland, Michigan

I appreciate the advice people like TMoore and everyone who have professional experience in the machinists trades give. I have come the other way, as a hobbyist who started with a small machine and has moved up to larger equipment. I am very pleased with my present project and will put up a dedicated post after I finish the cosmetic restoration.

This spring I bought a 1979 Bridgeport Boss CNC mill off of Ebay. It had been sitting in a shed for many years and the owner had no cnc knowledge. I paid $900 for it, plus another $100 for gas and trailer rental to get it to my garage. Other than looking like crap, and the dinosaur electronics shot, the machine itself was in good shape. There was no backlash on the ways or the ball screws, and the only mechanical thing I could find wrong was .001" runout on the spindle taper.

I ripped out all the old electronics and power supplies and used one of the control boxes to hold the new electronics- a 10amp 50volt lab power supply, 3 Gecko Stepper Drives, a Hitachi VFD, and power junctions and limit circuitry. The VFD allows me to run the spindle from single phase power and to fine tune the motor speed plus it gives me simple pushbutton spindle controls.

I added a quill-mount for a Dremel Advantage router and my vinyl plotter knife. Controlling it is a Panecon Industrial 486 PC running TurboCNC.

All told I have $2500 in the machine and it works perfectly. I plan to strip everything down now and do the whole machine in powder coat grey paint. Based on what they sell for (Ebay, again) the repainted mill should be worth $4-5000.

Hobby CNC does not have to be expensive, but you should look at what you need the machine for, and what it's total life cycle cost will be. It's one thing to spend $10,000 on a vacation to Hawaii. It is an entirely different thing to spend $10,000 on a good used CNC machine that you can sell after a few year and recoup most of your cost (not to mention make a little money with!)

By the way, here's a picture of the B-Port upon arrival at my house:



-Steven Balder
05-08-2006 Over year old.
HOMEPAGE  
 
 
OT45
Senior Heliman
Location: Kingston, NY

Nice purchase there sbalder! What size steppers are you using? I have an old Brideport and would like to retro-fit some day.
I would not bother with powder coating yours. You would have to strip everything off the machine, sand blast the old finish off and then bake the whole thing at temps that might mess with your "seasoned" castings. I would play it safe and just paint it with a good epoxy that is able to hold up to coolant and oil. Not to mention blasting can leave abrasive residue that is bad for moving parts if not all is 100% cleaned out. Anyway, your mill will be a nice versatile machine to make heli parts. Keep us posted on you progress.

-OT

scratch building is not just for planks
05-08-2006 Over year old.
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

Powder coat? Heck have you seen how neat his garage is. Check out his gallery, I make sure the wife's not looking over my shoulder when I look at his. She would harrase me to clean mine up until the end of time. You can almost move in mine and there seems to be a never ending supply of chips on the floor. I have to hand it to you sbalder I just can't seem to keep the same level of standards in garage neatness no matter how hard I try!
05-09-2006 Over year old.
HOMEPAGE  
 
 
sbalder
Senior Heliman
Location: Westland, Michigan

Thanks for the compliments on my shop. I am in the process of buying my dream house this summer, which will have a 3 car garage, dedicated workshop, and vehicle hoist. Almost forgot- 8+ acres for a private flying field.

I got inspired last night and tried my hand at powder coating the stepper motors in flat black. The process isn't too bad- with paint stripper, wire brushes, and brake cleaner I stripped the parts. Then I clean with Eastwood Pre-Prep solvent and dry with compressed air. Hang the parts, shoot them with the powder, and then "bake" in my improvised oven- an infrared shop heater, aluminum cookie sheet reflector and lots of duct tape and aluminum foil.

The steppers, by the way, are original "Slo Syn" brand, size NEMA 42. I have no idea what they are rated at, but I have my software set to run 100 IPM max.

Tonight I'll start on the rest of the machine...........

-Steven Balder
05-09-2006 Over year old.
HOMEPAGE  
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

8+ acres!! Around where you live now, buddy , pal....???
05-09-2006 Over year old.
HOMEPAGE  
 
 
OT45
Senior Heliman
Location: Kingston, NY

Cool, so the Eastwood system is low temp. I was wondering how well that system works.
100 ipm. Nice! Not bad for steppers.

scratch building is not just for planks
05-09-2006 Over year old.
 
 
TMoore
rrProfessor
Location: Cookeville, TN

Bridgeport's were done in the later years with Sherwin Williams Polane paint. Any good two part urethane would do fine. There is usually quite a bit of Bondo in the casting so be careful what you heat up.

TM
05-10-2006 Over year old.
HOMEPAGE  
 
 
Professorwiz
Veteran
Location: Livonia, Michigan - USA

Bondo can hold up pretty good to heat at least enough to bake paint on. Macco and most of the body shops now heat quick dry their paint. With those UV type powder coats they don't need much of anything at all.
OT45
I had a set of Nema42 steppers that were used on a bridgeport retro fit, unfortunetly I sold them off already when I was getting enough money up to try to fix my mill up. I needed a new spindle driver, but that's about the size I'd use I think they were around 720 oz/in. torque.
05-10-2006 Over year old.
HOMEPAGE  
 
 
springer454
New Heliman
Location: inverness

1987 bridgeport 412 interact pristene condition plastic cut only

i have a 412 interact fully enclosed
12 stc
flood coolant
15 hp rotor master all manuals all tools boatload
bobcad version 18
mastercam 9 educational version full functional
to mant extras to list have movie of it running
i have 10k invested ill sell for 7.5 this machine is in my garage ive drip feed it 3 thousand line programs using tnc remo h&h control 151
updated 2 yrs ago
nothing doesnt work this is a superb machine
that came from MACDEE in ann arbor michigan
i personall hand picked this machine out of 4 being sold
all they cut at macdee is PLASTIC / BODY PARTS
the cant cross contaminate materials in the body parts business
i hauled this home by my self on a car hauler pulling it with a v6 explorer WOW youi could not even see the explorer in front of the vmc
go to
web.tampabay.rr.com/donhartwich/
for a movie of it running
thanks
don

07-03-2006 Over year old.
HOMEPAGE  
 
 
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