Mill Suggestions?

[wheeler]

I looked in a catalog from Grizzly Industrial. They have every size and type of tool including the needed hardware. They have mill/Lathe combos that start at $795 and up to $2595(this one is 12"x39")

www.grizzly.com

[Bacchus]

I'd be careful with Grizzly... A lot of those tools are the "Chinese knock-off copies, most of which have real problems ranging from sand-filled castings to skewed table ways to horrible backlash problems on all axes. Avoid them like the plague." that Dave Lavery was talking about. On the other hand, their stuff is really cheap. I'd look around for people that actually own the tools and see what they think. And be prepared to return defective parts. When I bought a Horizontal Band saw from them the Hydraulic Feed was completely broken. They are really nice about this, and I got my replacement hydraulic cylinder in about 5 days, and I haven’t had a problem since.

[Doug G]

We got a Smithy Granite last year and it was a huge step up for us in terms of what we can now do (from hacksaws and hand drills). I agree completely with Dave that you must be prepared for the tooling costs. I think we've now spent more on tooling than on the original machine (4-Jaw Chuck, Rotary Table/Indexer, DRO, End mills, Collets, .....).

As far as Smithy quality - so far I've been impressed. The only trouble we've noticed is that the tolerances on the lathe are only +/- .002 on a good day and usually +/- .005 So much of it depends on how well you setup your pieces. We have had a retired machinist come in and show the students a lot of the basics.

Don't forget to reserve some $$ for quality measuring instruments and tools. Calipers, dial indicator, plunge indicator, Last Word, center/edge finder and their respective holders and bases.

Now I just need about two or three more, because during competition we have about 3-4 jobs lined up at any one time to get done on the mill. It's real easy to go over board with all this machining stuff, you keep saying things like "we'll just bore it open ourselves" and "we can make our own bearing pillow mounts". Remember this during the design process!

[Evan Austin]

I would also recommend looking around at local auctions. You can often find fairly decent machinery here and sometimes it will cost you less than buying a new cheap one. I bought a 10*36 Atlas lathe at an auction for 100 bucks. I also saw a fairly large South Bend lathe at the same auction that also went very cheap. I know you're looking for mills but the same thing applies. It is a game of chance, but if it is in good shape, it will work better and last longer than any of these new cheaper tools made today

[phrontist]

UPDATE: We bought the Rong Fu!. Came with a nice set of tooling, arrives in 8-10 days. Now we just need to learn how to use it...

[dlavery]

Congratulations! I think you will like the machine. As with any mill, you will need a big slug of tooling to go along with it. Some where back in my files, I have a list of all the tooling elements that go with a Rong-Fu mill to provide a good basic capability. If I can find it, I will send it along. Also, there are a lot of people in the NoVa area that have these machines (Team 116 included), that can help you get up to speed with it. Set up is pretty straightforward. If yours ends up being anywhere near as ready-to-go as ours was, you will just need to uncrate it, clean off the cosmoline, lube it up, tram the head, tighten up all the fasteners, and you are ready to go.

Make sure that when you mount it, you put it on a very solid, stable base. One of the biggest enemies of this class of machine is vibration, which will be amplified if the machine is sitting on a wobbly folded metal stand. Also, the perfect mounting location will have a hole in it so you can access the Y-axis acme screw from underneath the machine. This will make it very easy to periodically lube the acme screw without having to tilt up the machine (you CAN do this, but it is a bit of a pain).

These machines are heavy, about 600 pounds. To move the mill around (like putting it on your base when you uncrate it), an engine hoist is the perfect solution. If you don't have one in your shop already, you can get them locally at rental shops in the area for about $30/day.

-dave

[Matt Reiland]

Originally Posted by Doug G

We got a Smithy Granite last year and it was a huge step up for us in terms of what we can now do (from hacksaws and hand drills). I agree completely with Dave that you must be prepared for the tooling costs. I think we've now spent more on tooling than on the original machine (4-Jaw Chuck, Rotary Table/Indexer, DRO, End mills, Collets, .....).

As far as Smithy quality - so far I've been impressed. The only trouble we've noticed is that the tolerances on the lathe are only +/- .002 on a good day and usually +/- .005 So much of it depends on how well you setup your pieces. We have had a retired machinist come in and show the students a lot of the basics.

Don't forget to reserve some $$ for quality measuring instruments and tools. Calipers, dial indicator, plunge indicator, Last Word, center/edge finder and their respective holders and bases.

Now I just need about two or three more, because during competition we have about 3-4 jobs lined up at any one time to get done on the mill. It's real easy to go over board with all this machining stuff, you keep saying things like "we'll just bore it open ourselves" and "we can make our own bearing pillow mounts". Remember this during the design process!

I have a Smithy 1220XL Ltd and I can vouch that the accuracy of the factory ACME screws was terrible on my machine. I did upgrade mine to CNC and it was plain unacceptable. Just over the summer I upgraded the X and Y to Ball Screws myself from stock that I bought from MCMaster at quite a deal. Used a dial indicator and the transformation is Night-N-Day as far as accuracy. I think the machine overall isn't bad, just the screws on it suck especially since the brass half nuts on mine wore out so fast from the milled slots to support the power crossfeed. I did lose the power crossfeed but with the Ball Screw setup but I can get that with the Y CNC motor if I really need it.

[George]

HI, how is the rong-fu working out?
I have been setting up a jet drill/mill for use this year,
1) Installing a liner bearing on the head (so you can change hight without losing position,)
2) A "dro" on the spindle
3) reverse switch
4) chip shield with lights
5) collet rack

[sanddrag]

I just found this http://www.homier.com/default.asp?dp...tail&sku=03989 It is probably really junky and it has no z axis fine feed but at $199 it does seem to be a very good price.

[roboguy #1]

Well the mill we have is very nice its full cnc. I have a question if you cant run data from a comp. how can you cut round holes for bearings. Especially if you are using over 1" I believe we have 4 2" on our robot this year. But all in all digital cnc screen mpg all the goody's.

[KTorak]

See if you can find a "table top" bridgeport...our bridgeport floor models in our machine shop are very nice machines, with Digital Readouts for precision, and they are great to use as a drill press too.

[dlavery]

Originally Posted by sanddrag

I just found this http://www.homier.com/default.asp?dp...tail&sku=03989 It is probably really junky and it has no z axis fine feed but at $199 it does seem to be a very good price.

It all depends on what you want to do with it. If you are just going to knock out a few small pieces, and aren't really worried about precision or any workpieces larger than 2"x3"x6" then this might be OK. But if you are going to do anything involving multiple copies of the same part, quality finishes, tolerances closer than 15 mils, or ever working with plastics or other non-ferrous materials, then run away from this thing as fast as you can.

Here is a clue: if the vendor (Homier) doesn't even bother to proof-read their advertisements and make sure there are no spelling mistakes, just how much care do you think they put into their products?

Originally Posted by roboguy #1

Well the mill we have is very nice its full cnc. I have a question if you cant run data from a comp. how can you cut round holes for bearings. Especially if you are using over 1" I believe we have 4 2" on our robot this year. But all in all digital cnc screen mpg all the goody's.

For small round holes, multi-drill to 3-5 mils under size, then use a reamer. Do not just use a drill - a standard twist drill will give you a triangular hole (there is a good, concise discussion of this here). For larger holes, cut out the bulk of the material with a hole saw or mill, then finish with a boring head to get a hole that is truly round.

Machinists were making large round holes in workpieces for decades before anyone ever thought about how to control a cutting head with a computer. All you need is the right tooling, the right experience, and the right amount of patience. Machinists and toolmakers in the late 1800's were able to produce parts that were accurate to within a millionth of an inch when necessary, all by hand. Machinists - it is almost more accurate to call them artisans - could hand scrape a surface plate to a level of precision that would easily rival a Grade AA/Laboratory plate manufactured today. When computer control was added into the mix, it didn't really improve the precision or accuracy of the manufacturing process. The ability to produce a part to a certain tolerance was always there. But it did radically improve the speed of production for a given part (and particularly, multiples of parts).

Originally Posted by KTorak

See if you can find a "table top" bridgeport...our bridgeport floor models in our machine shop are very nice machines, with Digital Readouts for precision, and they are great to use as a drill press too.

As far as I know, Bridgeport never made a benchtop/table top milling machine. I believe that all of their models were floor-standing (this is certainly the case for all their Series-1 and J-head models). If you are talking about the mill/drill machines and smaller "laboratory mills" or "mini-mills" then you might want to check out the first part of this very thread, which already has a discussion on the topic.

-dave

[Doug G]

Originally Posted by dlavery

For small round holes, multi-drill to 3-5 mils under size, then use a reamer. Do not just use a drill - a standard twist drill will give you a triangular hole (there is a good, concise discussion of this here). For larger holes, cut out the bulk of the material with a hole saw or mill, then finish with a boring head to get a hole that is truly round.

Machinists were making large round holes in workpieces for decades before anyone ever thought about how to control a cutting head with a computer. All you need is the right tooling, the right experience, and the right amount of patience.

If you plan to press fit a bunch of bearings of the same size (ie... 1/2" ID = 9/8" OD, or 3/8" ID = 7/8" OD) Like we tend to do each year, it might be worth it to invest in an undersized reamers (from here. Last year we used a boring head to get our bearing holes the right size and it worked pretty well. We had a retired machinist last year helping / teaching us how to do some of the milling. We now have a small benchtop CNC which is so much simpler to make small transmission plates with bearing holes and such. The FP gearbox shown in this thread, was designed on a Wed. night (gears/bearings ordered that night), wrote the g-code on Thursday (with some help from MasterCam), received our gears/bearings on Fri, and had it finished Friday Night. We could have probably made the gearbox on our Smithy Mill, but we're so inexperienced, we'd probably just make a mistake, expecially since you need two sides to line up pretty darn close. The CNC is nice because once you have it set and indexed, it'll cut it out almost perfectly. Unfortunately our benchtop can only cut 3.25" on its y-axis, but it proved useful and is good for students to learn about.

[Validius]

This prolly wownt fit your budget but we use a Bridgeport with digital readouts. We didnt have to buy it cuz we have full access to Washtenaw Community College's machine lab (CNC's and all). I would agree that a digital readout is VERY nice.

Whats ur bandsaw like? We have one almost exactly like this one:http://www.usedmachinerysales.com/picture/2013.jpg

3 in ones are a pain. If you want a lathe, get a good one with the metal catch in the back for chips.

[roboguy #1]

Older Bridgeport you'll have to call them though.
I found this searching images on Google. Looks nice obviously used I will call looks like it may go cheap enough for you too buy its a Lil beat up. Hey you like Bridgeport? There you go.