Quill and head problems?

[NC Cams]

Welcome to the never ending search for perfection in a DIY machine.

The machine pictured in post 23 is using linear guides that are probably machine tool grade with preloaded balls. From my experience with nearly identical units (we bought 2 for to make our cam measuring machine) they run between $2500 and $3500 EACH. There is no slop and they definitely repeat. When you're measuring cams to 0.0001", you don't get away cheap.

When doing comparable tuning on our Bridgeport (we tried to use it cut cam masters, we learned essentially the same lesson re: moving the quill and/or table when doing precision cutting - you simply DON'T. The chances of moving up or down and holding X/Y positioning in a gibbs or sliding column quill are two - slim and none.

You can minimize it to maybe thou or two but as soon as you loosen the gibb, BOING, things move and you don't know where.

You can minimize it but if you really want accuracy, plan your cuts well and get rid if any hysterisis that you can but be respectful of the fact that you can't get rid of it all - not without replacing acme's with ball screws and gibbs with expensive preloaded machine tool grade linear ways.

[philbur]

I just checked an RF40 round cloumn. I can deflect the head +-0.002" by a not to agressive push/pull on the head. I didn't check the quill but I now from previous investigations its quite sloppy. These are things that are not easily fixed. But then everything will deflect when you apply a force, it's all a question of what you can live with.

Regards
Phil

Originally Posted by 1990notch Has anyone here done the same test with a round column mill? I'm curious if they will also move a similar amount when pressure is applied to the head.

[1990notch]

Phil - Thanks for checking your round column mill. Good to know. I'm tempted to get the round column HF (green) mill since it's cheap at $800, close by, has scraped ways and the belt drive has some good features in that no oil to leak and a 2500 RPM max spindle speed.

On the quill: When I used to use a Bridgeport, the only time I used the quill was when drilling, spot facing or plunging with an end mill or once in a while with a boring head. Other than that, I allways locked the quill and moved the table up or down as needed for making a deeper cut, etc. So I intended to use a square column in a similar manner, locking the quill and moving the head up or down as needed.

Originally Posted by philbur I just checked an RF40 round cloumn. I can deflect the head +-0.002" by a not to agressive push/pull on the head. I didn't check the quill but I now from previous investigations its quite sloppy. These are things that are not easily fixed. But then everything will deflect when you apply a force, it's all a question of what you can live with. Regards Phil

[wildcat]

1990notch - I used the HF mill you mention prior to purchasing the IH. I liked everything about about it except the round column. It did not seem to make a difference how careful I was in setting the head height initially there always came a point where I had to raise the head and on a round column that was very painful. Given the tolerances that you desiring you may also find a round column mill frustrating. I never measured it but I would be surprised if the round column I used was better than the IH. I know very well I can take much heavier cuts successfully with the IH than I was able to with the HF round column. HF has a square column for a little more or give the mini-knee mill I mentioned a few post up a look - it is very nice looking but I must admit that I have never used it.

[ViperTX]

Bob Warfield....apparently that Hurco was a stepper driven model....because the new one is servo driven and they (Hurco) mention that counterbalancing is not needed with the servo drive.

[Cruiser]

This will be my notes of my IH mill referring to the cantilevering and tollerance of the head "Z". I took a piece of tool steel (a damaged lathe tool holder) and using a 7/8" end mill, and took a prg'md path around the stock of nearly 1.25" depth and close to .15" d.o.c. and started with the material outside of cutter from column, i moderated the feed and it was all and good, then it came around the horn starting to buck and dance a bit then it went around again so matr'l is between cutte and collumn and the cutting force was enough to pick up the weight of the head and the cutter tried to walk on the material. I found out what i wanted to know, it was noisy and it did a real dance, but it did it ! after this i backed off to a more reasonable cut and it was smooth enough to be acceptable, then when i got to finishing, it was very docile during cut and when finished it was exactly on size and looked very good ! The part I was making was a key set to stake my kurt to the table, so there was a lot of matr'l to come off of the 1.5" tool shank i was cutting up. In the shop i work, even the Big Mills have issues, Am I impressed with what the IH mill will do ? YOU BETTER BELIEVE IT ! this is a lite machine yet powerful and full of capacity, did i say powerful ? I stalled a cutter in alluminum that i had clamped down solid ! and I moved the matr'l under the clamps with an end mill, I had to chuckle on that one, it caught me off gaurd but it didn't strain nor loose its position and the two clamps i had were tight as H**L before and after. I am assured that I purchased the Mill I wanted, it has great potential ! I won't be bothering with counterbalancing nor any other fancy, altho, I do have a potential idea of machining a box slide rail system to add onto the collumn and build a new saddle to accomodate it which would add rigidity to the collumn and eliminate any cantilevering etc. but that will be next yr before i possibly get to it, and it may not be called for exept maybe some roughing rigidity. . . MY personal opinion !

[hurcojohn]

viper...the counterweight vm1 was also full closed-loop servo driven, as all our machines are...it was first generation vm1, we now use a larger capacity servo motor (higher output) to drive the headstock,and no counterweight system.in fact none of our machines use counterweights any longer,even our largest machinery...many of the z axis servomotors incorporate a brake.

[1990notch]

Cruiser - Thanks for that post. I had a tip that the price would be dropping to $1500 on the IH mill today. I was trying to get a sense if I would be running into trouble down the road and what to expect. Your post helped ease my concerns alot. I ordered one today.