New Machine Build- Questions on various plans available

[JimPAC]

Lots of linear rails available for just your applications!

Round rails are considered best for plasma apps.

Stay away from steppers because everyone has a collision at some time.

Using a water tub with a good ventilator is best. Forget rolling outside unless you empty and then refill with water.

Good luck to you!

Jim

[millman52]

Originally Posted by JimPAC Stay away from steppers because everyone has a collision at some time. Good luck to you! Jim

Care to explain a bit farther???

I just this week watched a servo gantry run off then 1 side stop & the other keep going & destroy several dollars worth of hardware.

[Grumple]

Originally Posted by millman52 Most usually all you'd ever need the horizontal axis for is a gear or splines. I have a larger knee type mill with a NT 40 taper horizontal spindle. I've had it set up for splines 1 time in the last 5 years. On reviewing the specs of the mill you listed. The biggest issue for me is the vertical spindle will not run very slow. Most of my milling machine work is done at spindle speeds from 70-700. One of mine is a vari speed head range 60-4500 The other is a step pulley 16 speeds 75-3600 Second issue I don't see power feed on the vertical quill either. Almost a must for getting nice finish on holes you may need to bore. If you are limited to single phase power I'd much rather have this machine http://grizzly.com/products/Shop-Fox...9-x-49-/T20828 wouldn't be surprised if they are not built in the same factory. I'm sure the machine you listed is a far cut above the usual import table top mill/drill. The main reason it the weight you mentioned not wanting to deal with. In the machine tool word MORE weight ALWAYS = more stability. There are most usually many full size Bridgeport type mills with table size 9 X 42 & up for sale at or below that price range. The average 9 X 42 weighs in about the same. Then of course you need to know what to look for when buying used.

millman52,
That is the other machine I had my eye on like I mentioned in the post. Great points too. That is why I asked so I can get the best capability for my $$. I know the more weight the better machine for stability etc and either way I will need a fork truck rental to move it as my cherry picker was looking shaky when I unloaded my sheer and I don't need to drop my new mill when I get it. I want new as like you said, I want it to be right.
Thanks,
Grumple

[Grumple]

Originally Posted by JimPAC Lots of linear rails available for just your applications! Round rails are considered best for plasma apps. Stay away from steppers because everyone has a collision at some time. Using a water tub with a good ventilator is best. Forget rolling outside unless you empty and then refill with water. Good luck to you! Jim

I think I am going rack and gear drive with a ball screw for the THC. I did some research and steppers seem fine but I have heard about crashes too. Draining and refilling seems like a pain but if I know that before I build I can definitely put a good drain system on it just in case.
Thanks,
Grumple

[Torchhead]

Originally Posted by JimPAC Lots of linear rails available for just your applications! Round rails are considered best for plasma apps.

By whom?

I don't know anyone that considers round rails longer than about 36" to be best for anything. Plasma is more forgiving of flex and distortion because it's not a precision cutting process, but accuracy of a machine is the factor of ALL the errors added together. While it's true plasma is a dirty, nasty process and will foul any exposed surfaces any precision linear component is at risk. If you use the supported round rails and a partial wrap bearing (which will gain you the rigidity you need) you have basically the same structure as a standard square linear bearing.

Stay away from steppers because everyone has a collision at some time.

Huh? If you jam a stepper or hit a stop it just stalls....no harm no foul! It's not even required to have limits unless you just don't like the noise of stalled steppers (sounds bad but causes no damage)

The misunderstanding of how to properly gear and use steppers leads to the fear-mongering of lost steps and the incorrect blanket statements that servos are "better" than steppers. We sell and use (internally) both types of systems. We counsel the builders to match the usage to the type of drive and motors. Lighter gantries that are plasma only do not justify the added expense of servos. It's much like the argument of Gas VS Diesel engines. It all depends on what the end use is. There are distinct pros and cons for both types of systems.

It's Servos you have to be careful not to have a collision with. We put overload sensing on our servo power controls, so a stall will instantly shutdown power to all the motors. I have run my bigger servo based table into the stops (especially Z) accidentally several times. I have never damaged a motor, driver or anything on the table. With no power protection something will break or burn up.

Using a water tub with a good ventilator is best. Forget rolling outside unless you empty and then refill with water. Good luck to you! Jim

Now that I agree with.

[Dustin407]

Grumple, Are you going to design your table or just kinda wing it. If you need any design work, im more than glad to help. I specialize in autocad 3-D and could probably have your machine designed in less than 15 hours. Just make a parts list of everything you want to use... If your interested just post me back...

[Grumple]

Originally Posted by Dustin407 Grumple, Are you going to design your table or just kinda wing it. If you need any design work, im more than glad to help. I specialize in autocad 3-D and could probably have your machine designed in less than 15 hours. Just make a parts list of everything you want to use... If your interested just post me back...

Dustin,
How nice of you to offer your services for free I plan on doing it myself but I appreciate the offer. I have a few projects ahead of this that I need to finish while I get all the research on the plasma table. I plan ahead.
Cheers,
Grumple