Thread: Overhead router, metal mill or just another WOFTAM?

I posted this originally in Metalwork Forums but the machine has potential for overhead routing small timber items that can't be done safely on a router table, so I've reposted it here in case it's of interest to anyone.

I needed to cut two short slots in 6mm thick aluminium bar for bandsaw blade guides I was making.


I could have done a reasonably neat and perfectly adequate job in about half an hour with a twist drill bit, forstner bit to cut out the metal between the drilled holes, a file and the vice in my drill press. But my perfectionistic streak kicked in and I decided I needed neater slots, and if that worked then I’d have a machine I don’t have now that could do overhead routing in timber and with a different base could be a pin router. I couldn’t think of anything I’d need it for routing timber overhead or as a pin router, but it’d be there if I needed it.

So I thought I could use a retired Ryobi trimmer attached to the table on a drill press. This worked as proof of concept, but this set up suffered from poor visibility of the workpiece.



So I got a rusty but surprisingly still working old GMC drill press from a scrap metal merchant for $49 and removed the rust, then made this timber bracket attached to the drill press table to allow the bit to protrude further and improve visibility of the workpiece, which meant leaving the table in the usual horizontal position.



The problem with this set up is that the timber bracket doesn’t allow an accurate plunge function into the workpiece. Using the plastic shroud that came with the trimmer would improve the plunge function but just revert to the original problem of poor visibility. Also, it occurred to me to check the maximum RPM for the non-ferrous spiral downcut router bit, which is 24,000 RPM. The Ryobi trimmer is single speed at 30,000 RPM, so that was the end of that machine for this project.

But, luckily, among my vast collection of stuff that might come in handy one day was a variable speed (11,500 to 32,000 RPM) Ozito router that was retired hurt a few years ago after, despite very little use, the depth locking mechanism stripped the reverse thread in the alloy body. So I put a thread insert into the router and epoxied an Allen wrench into an Allenscrew as the new locking mechanism. Also in my vast collection of stuff etc was a 6mm steel plate near enough to the correct width for the drill press table and router, so that was cut to length;drilled for bolts to hold it to the drill press table and a hole cut for the router bit. The slotted bent aluminium pieces under the star knobs are travel stops for the cross slide vice, but if I’m going to use this much more I’ll re-do them in steel as the aluminium bends when the vice hits them and it needs visual rather than feel control to limit travel. Nothing in this set up involves a tool or machine doing anything it’s not designed to do, unlike using a drill press to mill, but it’s clearly limited to soft metals and timber unless I can find a router bit that will do mild steel and can also find the courage to use it.






Hole on left No.4 was first experimental slot taken at about .8mm a pass until cut through full depth and then enlarged progressively around the sides as a test until the bit grabbed the workpiece and twisted the drill press table about 15 degrees from horizontal and mauled the workpiece, apparently because I’d started the router when the bit was still in hard contact with the workpiece. No. 5 was the second cut and I was happy enough with it. The slight deviation at the bottom left of No.5 was because I thought it might be better to start with a hole drilled with a twist bit on the drill press, but the sides are more accurate if the router bit is just plunged into the work.




The end result is that I’ve spent $49 and at least the equivalent of a couple of days over more than a week fiddling around with this to get two neat slots that do exactly the same, albeit not as neat, job I could have done in half an hour. I’m not convinced this project wasn’t just another WOFTAM (Waste Of F#$%ing Time And Money).


That said, I now have a working old GMC drill press head with a broken quill spring that is exercising my mind on things I could make with it, or the parts in it. Or just add it to my vast collection of things that might come in handy one day.