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2003-01-18 by Zoran A. Scepanovic
Hi all, I'm on the way of making PCB drillin machine, and I would like to get some info on the spindle speeds and feed rates for different drill diameters needed for drilling FR-4/FR-10 boards. (Maybe Tom has the answer!) -- Sincerely, Zoran A. Scepanovic zasto@... [Non-text portions of this message have been removed]
2003-01-19 by twb8899 <twb8899@yahoo.com>
Zoran, There are calculations we used for the various feeds and speeds but most of this was done automatically by the machine. What you need to know is the chip load for the bit size you are using. The chip load is how many mils (.001" = 1 mil) the bit goes into the board per revolution. Your feed rate is then calculated by multiplying the chip load by the spindle speed. For example, a bit requiring a 3 mil chip load at 60,000 rpm equals 180 inches per minute feed rate. There are more calculations required to arrive at the surface feet per minute for a bit size etc. I don't know how to post these equations in this message because they are complex. There is a chart with all of this information on it and perhaps I can photograph or scan it into the Photos section. The bottom line on all of this is to just get your machine going any way you can and adjust the speeds for what works and sounds good to you. The Excellon drilling machines have a built in software page called a "Diameter Page" which contains drill bit size and feed rate information. This chart can be user edited to get the results you want. The machine looks at this chart and adjusts the spindle parameters as needed. These charts are set up in ranges such as .020" to .030" etc. Every size in this range will have the same feed and speed. If needed, the Diameter Page data could include a feed and speed record for every drill size you wanted to enter. Some CNC drill programs contain the feed and speed data from the CAD system and the drilling machine will use that info. The problem with this is I never once saw a CAD system that could get even close to having the correct feeds and speeds. So we always edited that part of the program and let the machine take over. An experienced machine operator will always tweak the spindle speed while the spindles are drilling until everything sounds right. You can actually hear the difference as you change the speed so you just keep tweaking until the spindles are "singing". The only time we got out all the charts and did calculations was when a customer was hanging around. This way they thought we really knew our stuff and were getting their money's worth! As soon as they left we went back to "winging" it!! We bent a lot of rules in those days to get the jobs out the door. It really was a lot of fun back in the old days. Anyone in the PWB business can tell you similar stories. Tom --- In Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic" <zasto@y...> wrote: > Hi all, > > I'm on the way of making PCB drillin machine, and I would like to get some > info on the spindle speeds and feed rates for different drill 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]
2003-01-19 by Zoran A. Scepanovic
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] ttyc> Be sure to visit the group home and check for new Bookmarks and files: ttyc> http://groups.yahoo.com/group/Homebrew_PCBs ttyc> To unsubscribe from this group, send an email to: ttyc> Homebrew_PCBs-unsubscribe@yahoogroups.com ttyc> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ And I replied: Tnx for info! I'll have to experiment! -- Best Regards, Zoran mailto:zasto@...