New benchtop mill

[RoboChair]

Originally Posted by protoserge

No. It is not.

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)

[protoserge]

Originally Posted by RoboChair

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 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.

12g can be bumped to 20A
10g can be bumped to 30A

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.

[rlowe61]

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.

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

[RoboChair]

Originally Posted by rlowe61

No matter what you buy, you need to ensure you have excess in your budget for Collets, Cutters, and a Vise.

But if you end up getting a bridgeport or any type large knee mill, a decent vise will run $200-$400 or more.

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

[protoserge]

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.

[techhelpbb]

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

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..

[asid61]

Originally Posted by RoboChair

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

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

[protoserge]

Originally Posted by asid61

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

Used Kurts are good if they work.

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

[RoboChair]

Originally Posted by asid61

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

$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.

[philso]

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.

[RoboChair]

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.

[JohnFogarty]

Can someone tell me if this looks worth looking into?

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

[RoboChair]

Originally Posted by JohnFogarty

Can someone tell me if this looks worth looking into?

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

It definitely looks to be worth taking a closer look at it. Call them and schedule an appointment to inspect the Bridgeport in person, it has a lot of good features on it but I can't see any detailed pics of the ways. If you can see the flaking marks on the ways and it feels mostly smooth up, down, left, right, front, back, quill up and down, DRO functional. If that all looks good then it would be a great machine.

[Cory]

Originally Posted by RoboChair

It definitely looks to be worth taking a closer look at it. Call them and schedule an appointment to inspect the Bridgeport in person, it has a lot of good features on it but I can't see any detailed pics of the ways. If you can see the flaking marks on the ways and it feels mostly smooth up, down, left, right, front, back, quill up and down, DRO functional. If that all looks good then it would be a great machine.

Generally any government surplus machine that makes it to public auction is a piece of junk. Every federal agency and then state agency had a Crack at it and passed. Tons of govt surplus material sits outside completely unprotected from the elements as well. This mill doesn't look like it had that problem, but be wary.

Originally Posted by Tyson

Kent
Having a local distributor in orange county is a benefit I suppose.
http://www.kentusa.com/mills/

Kent is the same rebadged Chinese/Taiwanese machines as every other brand. They are by no means a premium brand.

From everything I've heard, Sharp is the best Asian clone (the high end Acras are the same as Sharp).