Multi-spindle CNC drilling machine

[Fudd]

Has anyone designed a multi-spindle CNC drilling machine. I have a large number of plates that I am going to need to drill on a regular basis and would like to design a machine or retro-fit one to drill 3+ plates at a time. If someone has done this could you share your design? What would you use for a spindle? Holes are .086" diameter.

Thanks,

Scott

[DareBee]

Should be simple to make, not necessarily cheap though.
The ultimate option is to build with autodrills (see picture), this saves the issues involved in needing a large Z axis platten to hold multiple spindles as they self feed, unit is about $4k.
The pnuamatic autodrills are significantly cheaper but use a LOT of air and are noisy.
If you want to take on the task of designing a Z platen to mount spindles on A really inexpensive method is to buy ready to use spindles from Sherline Industrial product line. About $400 each.
Another decent option is to use Nema 23-34 perm mag DC motor. use the output shaft as one end of the spindle and design a bearing at the output end of the shaft that incorporates thrust load capabilities.

Enough about spindle ideas.
Designing a good industrial quality Z axis is no small task and is not inexpensive, if you only need 4-5 drill spindles I strongly urge the autodrill route. My last project needed 14 drill spindles - I did design a Z axis for that job to keep costing down about.
The spindles and Z are the big hurdle, adapting a machine table and doing XY positioning is fairly straightforward.

[wizard]

Hi Scott;

Info here is a bit thin. When you say multiple plates do you mean on top of each other or side by side? The whole diameter is small but you use the word plate which implies to me some thickness. Further is it one hole per plate or a series of holes? I'm trying to figure out the need for CNC here.

I ask because you can buy machines with multiple spindles to do what you are asking. to be honest though I'm not sure how they would work with the small diameters you are talking about. The issue with multiple spindle machines is that the spindle arraingement is fixed at least in most cases. There are also CNC drilling machines, sort of like a mill but optimized for drilling. Generally these do a piece at a time, though with good fixturing you might get three pieces done at a time. There are also attachments for drill presses that will give you multiple spindles.

You are thinking about retro fits so I'm thinking small parts or low quanity, thus not justifing a purchase of new equipment. Depending on what exactly is being done with the plate and its size I'd suggest two small mill drills for conversion. Then you could do two plates at once and overlap your load cycles. You might possibly hae enough horse power to drive two spindles at once to get four machining operations going.

Another option is air turbine spindles attached to a mill headstock. I mainly thought about this due to the small diameter of the holes you are interested in. Go beyone one spindle per machine though and you are back to the issue of alignment and getting the same results against all plates. If you want simple and precision, I'd still think about one spindle and just get more machines. If precision isn't an issue then maybe the multiple spindle approach will work.

Thanks
Dave

Originally Posted by Fudd Has anyone designed a multi-spindle CNC drilling machine. I have a large number of plates that I am going to need to drill on a regular basis and would like to design a machine or retro-fit one to drill 3+ plates at a time. If someone has done this could you share your design? What would you use for a spindle? Holes are .086" diameter. Thanks, Scott

[Fudd]

The plate is .5" thick and will have 1433 holes in about a 5" diameter circle. I would be doing hundreds fo these plates and using speeds and feeds data each plate would take 6-8 hrs. Speed would be around 1700 rpm. I currently have 2 VMC's, but they would only do one at a time.

Thanks,

Scott

[DareBee]

1700RPM?
Don't you mean 17,000 RPM

[Fudd]

Darbee,
The drill manufacturer calls for 40 sfm. Approxs. 1700 rpm. Correct?

Thanks,

Scott

[DareBee]

Well I get 1910 but I think you should try different drill manufacturer and get some speed going.
An UltraTool Ultra-Carb drill is 100-200 SFM and add 15-20% with TiAln coating, even the lowest SFM is 120 so that is 5700RPM and at .0015 chipload that is 17.2 IPM (you may be able to get chipload as high as .003).
Granted, you still have a big job ahead of you but this just tripled your output and is still on the conservative side.
Scott - I would be happy to help you machine these.
Derek

[Fudd]

Are those numbers for 17-4 PH? That is what the material is.

Thanks,

Scott

[DareBee]

SFM 30-90 the +20% and everything else still applies. So now you are at 5700RPM top of the scale. With PH you probably want to work your feedrate at the high end.
Anyway, I am sure you already know all of this.

[Fudd]

DareBee,
No, I do not. I have not worked with 17-4 PH. Have you worked with it alot? I was told to look toward Guhring drills and the factory quoted me 40 sfm .002-.003" IPR. I will be drilling through .5" plate. What drills do you recommend? I was going to use a parabolic drill. What about pecking and do I need to spot 1st?

Thanks for the help,

Scott

[DareBee]

Sorry Fudd I have no experience with PH, I am drawing my reference on similar types of material I have had the pleasure machining.
With as many holes as you have to do I would suggest getting a high end tooling supplier in and go by their recomendations, they usually put their money where their mouth is and bring samples and actually help you run untill you are happy with the outcome.
If you are drilling rough cast you probably will need to spot the holes but maybe the supplier will tell you otherwise.
The high grade tooling I have readily available here may not be as easy to get where you are at.
Sorry I can't really be of more help.
My offer to run some of these parts still stands (I am kinda slow right now).