Re: New benchtop mill
 

I mirror the RF45 recommendation.
These have R8 spindles like the Bridgeport.
http://charteroakautomation.com/our-.../cnc-bed-mill/

That said, I have a highly modified Sieg X2 and have used the stock Sieg X3.
These have R8 spindles like the Bridgeport.
If you get one in good shape they can hold 0.001".
http://www.siegind.com/products_list/&pmcId=29.html
http://www.hossmachine.info/
Tool changer

I also own a ShopMaster Patriot VFD post-2012 mill/drill/lathe that I got for $4,000 with shipping used complete with CNC.
My machine takes 220V and has 1 VFD and 2 drive motors.
These have R8 mill spindles like the Bridgeport, MT3 for the lathe tailstock.
These machines support rigid tapping.
They can have sensors put on both the lathe and mill to 'close the loop' for RPM through the control PC.
http://www.shopmasterusa.com/content...-1-machine-cnc
The latest model just sold on eBay for $5,600 because a school ordered some and the funding fell through.

Also I've seen Tormachs here and there in the $5,000 range.
http://www.tormach.com/

I own both a MaxNC10 and MaxNC15 CNC min-mills with 4th rotary axis.
These are like Taig and Sherline.
They are a good tool for small jobs and could be used for jewelry making and aluminum gear making.
I wouldn't necessarily make robot sides with it because the travels max out at 16".
http://www.maxnc.net/category_s/1817.htm

You want to make sure with the Chinese mills you can get support after the sale in case you have defects.
I hesitate to buy any used, 'been laying around almost new', Chinese mills because you don't know they were ever tested.

You don't need a mill deck the length of the side of your robot: if you put a guide on the back of the deck and dowel pins at the extreme travels. You end up with some extra holes but you can then support the over-length on rollers. Just tile the operations.

Re: New benchtop mill
 

Fair point, but I think in most cases bumping it up an extra 5A will be well within what the wire is good for.

Re: New benchtop mill
 

No. It is not.

Re: New benchtop mill
 

I will admit that that was a sweeping statement I made about the circuit layouts, sorry about that. You will often see smaller breakers in the panel than the wire can handle, before we had our former classroom turned shop rewired it had a LOT of 10A breakers when the wire gauge could have handled 15A.

If you have a 10A breaker, there are no problems on the part of the 14g wire upgrading it to a 15A breaker. A 2 HP(1500 Watts) Bridgeport at peak amperage being run via a VFD is 12.5A @120V even with efficiency losses you would have to be pushing that mill very hard to hit 15A (1800 Watts).

12g can be bumped to 20A (2400 Watts)
10g can be bumped to 30A (3600 Watts)

Re: New benchtop mill
 

I thought you were saying to change a 15A breaker to 20A. That would be a terrible idea. I have seen it done before and had conduit that was hot to the touch. Sorry for the confusion on my part.

Re: New benchtop mill
 

Not trying to discourage in any way, but I have a few points when buying a Mill.
Everyone is talking power so I'll leave that alone. :deadhorse:

No matter what you buy, you need to ensure you have excess in your budget for Collets, Cutters, and a Vise. Depending on what your plans are you can get a set of cutters from Harbor Freight that will do sufficiently on aluminum. Collets, here is a good portion of money you need to spend. R8 collets are pretty much the standard for most bench tops. You'll need any where from 5 - 8 depending on your cutter shaft. commons are 3/8, 1/2, 5/8 and a few more. If the mill doesn't come with digital read outs, I'd highly recommend buying a set and installing them, as the slop in the cranks is always there and only gets worse.
A Vise, for most table top mills a small vise is all that is needed. But if you end up getting a bridgeport or any type large knee mill, a decent vise will run $200-$400 or more. A full set of mill clamps (T-Nuts, studs/nuts and clamps) can also add to the budget.

Someone asked about a knee mill, Katy ISD has a JET knee mill in the STEM Center for the teams to use. I know 624 (CRyptonite) and a couple other teams used it extensively this year. I can provide further info.

Have fun and happy cutting:yikes: :)

Re: New benchtop mill
 

Shars.com for good quality cheap tooling

As for a Vise, the Kurt Scratch and Dent discount vise comes highly recommended. You will not regret your purchase.
http://www.amazon.com/D688-SD-6-inch...qid=1460749066
Two words: FREE SHIPPING

Re: New benchtop mill
 

No need for cutter sets. Buy a few HSS 1/8", 1/4", and 1/2" end mills and collet holders to support it.

I like the Shar's 4" precision vise for the price, but you can get Glacern for a great price in November (at least this past year and two years ago). Most boring heads that look like Criterions are junk. eBay the real thing if you need one.

Re: New benchtop mill
 

Common machine tool accessories you might buy for a lathe or mill:
(no additional costs to notice here...just move along :yikes:)

R8 collets (25 imperial sizes are common)
MT2 collets (23 imperial sizes are common)
MT3 collets (23 imperial sizes are common)
5C collets (64 imperial sizes are common)
Sherline/Taig/MaxNC 3/8"-16 collets (8 imperial sizes are common)
ER16 collets (12 imperial sizes are common) Note 1
ER20 collets (14 imperial sizes are common)
ER25 collets (16 imperial sizes are common)
ER32 collets (25 imperial sizes are common) Note 2
ER40 collets (25 imperial sizes are common)

ER16 tool holders and wrenches
ER20 tool holders and wrenches
ER25 tool holders and wrenches
ER32 tool holders and wrenches
ER40 tool holders and wrenches
CAT40 tool holders and tightening stand
The tool holder list can go on and on: CAT50, CAT60, Brown&Sharp
* Note 3

Note 1: ER16 is often the actual spindle for small machines like the MaxNC.
Some also use 3/8"-16 collets. The ER16 collet holder has a small
outside diameter that makes it easier to plunge into tight spaces.

Note 2: ER32 has a pretty large outside diameter, but can holder larger
diameter tools.

Note 3: Notice I didn't mention metric ;). Also there are things like ER20-GB collets.
These collets have a square in the back to engage the square on the taps.

Edge finders (mechanical or electronic)
Probes
1-2-3 blocks
Tombstones
Micrometers
Squares
Dial indicators
Dial test indicators
Feeler gauges
Torque wrenches (collets, draw bars)
Calibration rings
Granite test blocks
Gauge blocks (you know that perfectly sized test piece you just welded into the robot as scrap!)

Center drills
Square nose end mills
Ball nose end mills
Jobber drill bits
Aircraft drill bits
Split point drill bits
Countersinks
Boring bars
Carbide bars (lathe)
Indexed cutters
Punches
Fly cutters
Slitting saws
Hobs

Rotary broaches
4th/5th axis
Ball turners
Dividing heads
Rotary tables
Tool makers vises
Sine vises
Pin vises
V-Blocks
Down force milling vises
Boring heads
Taping heads
Rigid tap holders
Self-centering chucks
Independent jaw chucks
5C collet chucks
Tail stocks
Live centers

Bottom taps
Plug taps
Gun taps
Tap/drill combos

Broaches

Vortex coolers
Mist coolers
Drip coolers

CAM software
CAD software

That's just a tiny little start...this is the tool buying that never ends...it goes on and on my friend..

Re: New benchtop mill
 

What are your thoughts on used Kurts? Machine shop auctions inevitably have them go for <$150.

Re: New benchtop mill
 

Used Kurts are good if they work.

Enco sells Kurt so you can get them new at 25% off as well.

Re: New benchtop mill
 

$150 is only for the exceptionally patient bidder. But buying used is perfectly fine and is most of what we do for major items. You need to know what you are looking for and also what you are looking at, otherwise you could end up spending too much for something that is way more than you will benefit from or of poor quality for the price.

Re: New benchtop mill
 

If you are getting a VFD, watch out for the following:

• Get the VFD sized properly based on the motor's rated current (look at the motor name plate). If the VFD is rated for operation at different input/output voltages, the current rating is still the same, no matter the voltage (i.e. a VFD rated for 10A at 480V is still rated for 10A at 240V).

• If the VFD you are buying is rated for operation with a single-phase source, you are good to go. If it is only rated for operation with a three-phase source, you will have to get a VFD rated for 173% more output current or you may blow out the input rectifiers.

• If your budget can handle it, get the next larger VFD to have a bit more margin. Many are built down to a price and have very little margin.

• Install the VFD where metal dust and shavings cannot get into it, otherwise, it can be permanently damaged. The same thing would happen to the Jaguar's of several years ago but VFD's store much more energy and can sound like a shotgun blast when they die. If you can see through slots in the VFD's enclosure and see circuit boards and other components, it can be damaged this way. A good place to mount a VFD would be up high on a wall above the mill. Most VFD's have inputs so that you can connect start and stop switches and mount those next to your mill. If you must mount it where metal dust/shavings can fall on it, install it in a sealed metal box with a stirring fan. The box needs to be large enough to dissipate the heat generated by the VFD. The VFD vendor should be able to help you select a box of appropriate size (based on the VFD's heat output, the dimensions of the box and the sides that are exposed to the air). If they cannot help you, PM me and I will get the formulas from our Applications Department.

• A motor does not have to be VFD-rated to be used with a VFD. VFD's generate high voltage spikes that speed up the break down the insulation in a motor over many years of continuous use. VFD rated motors are manufactured with stronger/thicker insulation to resist this and are usually a bit more expensive and may be a bit harder to get. A mill for an FRC team will probably not see enough use for this to really matter. Many of our customers (my employer is a VFD manufacturer) do not use VFD-rated motors.

If you are setting up a home shop where you usually have only one person operating only one piece of equipment in the shop at a time, you may want to consider putting an appropriate in-line receptacle on the VFD output. You can then convert some other pieces of equipment to run on the same VFD and control the speed with a 10-turn pot. Drill presses run on a VFD are really sweet to use. No more swapping the belt around when going from a 1/8" bit to a 1" bit.

Re: New benchtop mill
 

This California bay area auction just went up.

http://www.westauction.com/auction/m...hine-shop-1474

If you PM me I might be willing to proxy for some of the more shippable items, inspect specific items, or pick up stuff if you are too far to drive. If you register to bid on anything please make your user name obvious that you are a robotics team (eg. FRC1678), don't want to get in bidding wars with other teams.

Re: New benchtop mill
 

Can someone tell me if this looks worth looking into?

https://www.govdeals.com/index.cfm?f...d=1055#me dia