New benchtop mill

[vigneshv]

Hi,
We are looking to buy a benchtop mill in the offseason. Does anyone have any recommendations on which mills would be best for FRC use? Our budget is around $5000. Thanks!

[cadandcookies]

I'm just going to run through the standard CD checklist for mills:

1: Does it have to be a benchtop? Do you have room for a full knee mill like a Bridgeport?

2: You should probably count on spending at least as much on tooling as on the machine.

3: Do you have a mentor or a contact who knows how to use a mill? The nicest machine in the world won't do you any good if you don't know how to use it.

4: Whatever machine you get, it's probably worth taking it apart and cleaning it up. You can look up details for whatever model you end up getting online.

5: At some point, Cory might post in this thread. If he does, listen to what he says. He knows what he's talking about (much more so than I do).

6: The search feature is your friend. A quick search for "benchtop mill" produced a ton of results. Here are a few you might find relevant:

[1] [2] [3]

It's definitely worth reading through some of these old threads-- most of the info is still relevant.

Best of luck with your search!

Edit: Based on those old threads, I'd look into a RF-45. Grizzlys work but... Well, the one in the metal shop where 2667 works is pretty much perpetually broken and the Bridgeport has been trucking since probably before I was born, so make of that what you will.

[Ian Good]

This thread and this thread should be able to help you!

Also I did a little bit of digging around and I found this

That seems to be a decent mill with a Digital Read Out for really cheap (!!!)
I don't own one so I can not attest to the quality of the mill however we have been using Grizzly tools in our shop for years and we've never had a problem.

[Cory]

RF-45 is the highest quality readily available benchtop mill you're going to find. It's pretty pain free to use and can legitimately make good parts (especially with DRO), but it is small, doesn't have much z-travel, and changing tools can be annoying.

It's well within your budget, but you could also be looking at bridgeports/bridgeport clones with your budget, if you have space.

[RoboChair]

Buy the most machine that you can afford and make space for, machine performance to price ratio is non-linear(eg. 2x$$$=4xMachine). If you want advice on tooling and/or buying a full sized machine used, please do not hesitate to PM me. Some people around here might say I buy too many machines >_>

[asid61]

Originally Posted by Cory

RF-45 is the highest quality readily available benchtop mill you're going to find. It's pretty pain free to use and can legitimately make good parts (especially with DRO), but it is small, doesn't have much z-travel, and changing tools can be annoying.

It's well within your budget, but you could also be looking at bridgeports/bridgeport clones with your budget, if you have space.

Seconded. The RF-45 has a dovetail column, which is a must IMO for drilling and milling on the same machine (which you will do). Whatever you go for, avoid round column mills.
Make sure you bolt these down, especially if you put them on the flimsy sheet metal stands they come with. I've found that as little as turning the handles too fast makes it shake and throws it off as much as 0.005" on the spindle.

[sanddrag]

Who makes the best Bridgeport clone these days?

[protoserge]

Why benchtop when you have budget for a knee mill? Is tooling factored into the budget? A knee mill isn't much more of a footprint on the largest benchtop type.

PM-940 from machinetoolonline.com would be my recommendation if you have to get a benchtop type. Ask about getting a variable speed spindle for it. PM-935 knee mill is made in Taiwan and would be even better if you can swing it. Both are 240V.

Enco has yearly 25% off sales that include machinery with free shipping. You could get a great deal on one of the knee mills if you sign up for their newsletter. I believe the Turn-Pro brand is Taiwanese.

[JohnFogarty]

I was going to be going back through the content of these threads looking for some recommendation for 4901's new machining equipment.

One thing I have to ask is there a good knee-mill that uses single phase power? There's no way my team can get a 220V+ hookup in our shop.

[vigneshv]

Originally Posted by JohnFogarty

I was going to be going back through the content of these threads looking for some recommendation for 4901's new machining equipment.

One thing I have to ask is there a good knee-mill that uses single phase power? There's no way my team can get a 220V+ hookup in our shop.

We have the same problem, we were originally looking at knee Mills, but we found we couldn't meet the 220V power requirements.

[protoserge]

220-240V is typically single phase. 208-230V is typical three phase.

You can get static phase converters pretty cheap these days. If the motor is rated for inverter duty, you can get a variable frequency drive.

If you only have 120V available, there are VFDs for running three phase 208-230V motors, but you are limited in power.

A lot of knee mills are single phase, just check the motor nameplate.

[JohnFogarty]

Originally Posted by protoserge

220-240V is typically single phase. 208-230V is typical three phase.

You can get static phase converters pretty cheap these days. If the motor is rated for inverter duty, you can get a variable frequency drive.

If you only have 120V available, there are VFDs for running three phase 208-230V motors, but you are limited in power.

A lot of knee mills are single phase, just check the motor nameplate.

We only have 120V availible.

[protoserge]

Originally Posted by JohnFogarty

We only have 120V availible.

You might be able to get a 1-1.5HP 208 3 phase mill and run a properly rated 120V single phase to 208V three phase VFD. Your maximum current draw (I estimate 9-10A for a 1.5HP on 120V) may be closer to the limit of the common 15A 120V circuit than you'd like.

I believe most knee mills use standard frame motors, so getting a working solution (120V motor) may not be that big of a deal. If it came between making a knee mill work on 120V or getting a G0704, I would get the knee mill and live with the 0.5-1 HP compromise.

[Tyson]

Originally Posted by sanddrag

Who makes the best Bridgeport clone these days?

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

[frcguy]

Originally Posted by 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.

Just saw this auction. What are the worthwhile items for an FRC team? Does that Haas VF-1 have any use in FRC? That and the manual mill particularly perked my interest.

Edit: Here is the link for the Haas