haas linear scales

[1320feet]

Haas offers linear scales as an option.

What would be the adavantages of this option?

I would also like some opinions on there VF4SS machine?

 

Thanks

Howard

[Kevangel]

I have been told the advantage is it controls thermal expansion but does NOT NOT help on jig-boring capabilities on low cost CNC machines like putting a readout on a Bridgeport with worn leadscrews. The disadvantages can be added cost and contamination. If they tell you it will help on Jig-boring capability, ask them "how much" and tell them you will need it "in writing" what they will guarentee on true position hole boring.

[Kevangel]

Also on cheaper machines its not the scales that are incapable, but rather something about getting the "most bang for the buck" when they buy Drives and the boards that control them and the 200K machines may not suffer this same problem. I have gone round and round with manufactures on this and in the end they say "no, scales on a low cost VMC will not replace a jig-borer when that accuracy is needed". Something about drift. This was 5 years ago and maybe things have changed. Nothing like asking for what the say it will hold, in writing, to eliminate the BS.

[FP1]

I've been around the cnc machine tool trade for alot of years. I think the weight/thickness of the machine tool casting has a lot to do with the accuracy a machine can hold. I think the thinner castings are more effected by thermal growth and can twist more easily

 

Some years ago I was in the market to buy a pair of good lathes for turning large brake drums and hubs. I found a significant difference in the weight of comparable models from different manufacturers. Mazak SL-35/13,500 lbs - Mori SL-35/17,500 lbs - Okuma LB-35/21,500 lbs. There was a big difference in dollars too. The Mori was 20% more than the Mazak. The Okuma was twice as much as the Mori but the Okuma dealer wouldn't budge from list price. I bought the two Mori SL-35s. I would have bought the Okumas even if they were 10% more $ than the Mori. Oh well, their loss. Just my $.02 worth.

[Guest]

quote:

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Haas offers linear scales as an option.

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Lipstick on a pig, still makes it a pig

[SydwazShawn]

The SS machines use the same encoder on the X,Y axis drive motors as they do with there non SS machines. The only difference is the pitch of the ball screw. On the SS machines if you were to take a tenth indicator and zero it out on a face, then move it to another known dimension face in the same direction, you can easily get a .0008 or more deviation depending on were the encoder tells the ball screw to stop. Same goes for the backlash.

[Chris Rizzo]

What Shawn says. we sent our ss back for that reason.

 

Gene Haas deserves to be in prison as punishment for the dam SS machines alone, nevermind what he is actually there for.

 

I can't imagine what their definition of "glass scales" are....sounds like someone at haas is smokin' a glass pipe.

[Thee Dragracer1951]

quote:

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Lipstick on a pig, still makes it a pig

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[mgsanchez]

Haas "claims" 1 micron accuracy for their linear scales option. Linear scales on a Haas do not control thermal expansion, but more like it compensates for it. Lighter castings will move and flex more. Since the "scales" are mounted to the castings, the moving and flexing will compromise the scales accuracy.

 

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[mgsanchez]

Oh, by the way, the linear scales will not compensate for spindle growth issues inherent in a Haas.

 

.

[bigjohn]

quote:

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Lipstick on a pig, still makes it a pig

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LOL

[Jerosu]

quote:

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Gene Haas deserves to be in prison as punishment for the dam SS machines alone, nevermind what he is actually there for.

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LOL

[GoetzInd]

Try a coolant chiller.

[kunfuzed]

Tommorrow I get to hold a .001 Position Tolerance on two bored holes on our new VF-11 !

 

And that's with stoping in against dowell pins! Not machining the datums at the same time.

[#Rekd™]

Hey JP,

 

"Lipstick on a pig, still makes it a pig"

 

That is to freakin funny man but true...

 

John Ford

 

GIT

R

DONE

[Guest CNC Apps Guy 1]

quote:

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....001 Position Tolerance on two bored holes... And that's with stoping in against dowell pins! Not machining the datums at the same time.

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That's going to be a chore no matter what machine you're doing it on. Why on earth would you have to do such a thing that way???

[kunfuzed]

 

Over... over... over-engineered. Were building some sort of blade cradle for checking the twist in S-64 tail-rotor spars that are being manufactured in house now. Funny thing is, the dimensions on the profile where the blade rests are +/- .01!!!

 

These two holes get drill busshings pressed in, and thene aligned with dowel pins to another part with pressed bushings and the same hole locations.

[kunfuzed]

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Why on earth would you have to do such a thing that way???

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Which part? You mean why finish the profile, and then reload them later to finish the locations?

 

The higher ups seem to think this is the best way. We started with 5/8" plate, roughed the profile, fliped, faced, flipped down to 1/2", then finished the profile. I think the theory is to get all the meat off so the part gets all the stress out and doesn't move. I hate dealing with plate, never anything to hold on to!

[Joseph]

You will probably have better luck if you approach both holes from the same direction.

Temperature matters, thermal expansion makes a big difference on big parts. Is it possible to finish one hole, rough the other and let your inspection dept. tell you how far to move the last bore?

[kunfuzed]

Actually these are small parts. About an 8 inch spread between the holes. The part is L shaped with a hole at each end. We are using a positive aproach befor the boring cycle.

 

All the holes have been piloted .002" under, and we could do a cmm report, and indicate to each one and adjust, but we have about 20 of these parts to do, and they think we can do them faster by slapping them into a fixture and hopefully hold location.

 

I just did my first one. One hole was within .0008 total, the other .0006. We'll se where the next one lands.