Hello twb8899,
19. January 2003, 21:48:33, you wrote:
ttyc> Zoran,
ttyc> There are calculations we used for the various feeds and speeds but
ttyc> most of this was done automatically by the machine. What you need to
ttyc> know is the chip load for the bit size you are using. The chip load
ttyc> is how many mils (.001" = 1 mil) the bit goes into the board per
ttyc> revolution. Your feed rate is then calculated by multiplying the chip
ttyc> load by the spindle speed. For example, a bit requiring a 3 mil chip
ttyc> load at 60,000 rpm equals 180 inches per minute feed rate.
ttyc> There are more calculations required to arrive at the surface feet
ttyc> per minute for a bit size etc. I don't know how to post these
ttyc> equations in this message because they are complex. There is a chart
ttyc> with all of this information on it and perhaps I can photograph or
ttyc> scan it into the Photos section. The bottom line on all of this is to
ttyc> just get your machine going any way you can and adjust the speeds for
ttyc> what works and sounds good to you.
ttyc> The Excellon drilling machines have a built in software page called
ttyc> a "Diameter Page" which contains drill bit size and feed rate
ttyc> information. This chart can be user edited to get the results you
ttyc> want. The machine looks at this chart and adjusts the spindle
ttyc> parameters as needed. These charts are set up in ranges such as .020"
ttyc> to .030" etc. Every size in this range will have the same feed and
ttyc> speed. If needed, the Diameter Page data could include a feed and
ttyc> speed record for every drill size you wanted to enter.
ttyc> Some CNC drill programs contain the feed and speed data from the CAD
ttyc> system and the drilling machine will use that info. The problem with
ttyc> this is I never once saw a CAD system that could get even close to
ttyc> having the correct feeds and speeds. So we always edited that part of
ttyc> the program and let the machine take over.
ttyc> An experienced machine operator will always tweak the spindle speed
ttyc> while the spindles are drilling until everything sounds right. You
ttyc> can actually hear the difference as you change the speed so you just
ttyc> keep tweaking until the spindles are "singing". The only time we got
ttyc> out all the charts and did calculations was when a customer was
ttyc> hanging around. This way they thought we really knew our stuff and
ttyc> were getting their money's worth! As soon as they left we went back
ttyc> to "winging" it!! We bent a lot of rules in those days to get the
ttyc> jobs out the door. It really was a lot of fun back in the old days.
ttyc> Anyone in the PWB business can tell you similar stories.
ttyc> Tom
ttyc> --- In
Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic"
ttyc> <zasto@y...> wrote:
>> Hi all,
>>
>> I'm on the way of making PCB drillin machine, and I would like to
ttyc> get some
>> info on the spindle speeds and feed rates for different drill
ttyc> diameters
>> needed for drilling FR-4/FR-10 boards.
>>
>> (Maybe Tom has the answer!)
>>
>> --
>> Sincerely,
>> Zoran A. Scepanovic
>> zasto@y...
>>
>> [Non-text portions of this message have been removed]
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http://docs.yahoo.com/info/terms/ And I replied:
Tnx for info! I'll have to experiment!
--
Best Regards,
Zoran
mailto:
zasto@...