Over the Operation That Scared Me

Not surgery.  I'm over the drilling operation I needed to do for the oil hole in the cross slide, the operation that scared me the most.  I've written before about the 4" long 1/8" diameter hole I need to drill.  It's complete. 

Before I go on, I'd be remiss if I didn't do a hat tip to a frequent commenter here, who usually posts by the name of John.  John reached out to me via email some time ago on some project and we've kept up correspondence.  John also happens to have been a mechanic in the Navy and had some experience with hydraulic systems that make this one look like child's play so I asked him for some advice and he largely redesigned the system on the fly.  That included adding some details that made it easy to go on a net-based shopping trip to find all the fittings I need. 

The main difference is to recognize that while Hoss referred to 1/4" tubing, unlike plumbing (which has its own oddities - like pipe size "schedules"), these little tubes are either specified by their OD or their ID, depending on the seller.  That spells TROUBLE to me.  I searched for table of actual sizes for these tubes and found 3 different IDs for a 1/4" OD or 3 different ODs for a 1/4" ID.   John's main recommendation was to go to fittings on the cross slide that screw into a standard pipe taper threaded hole.  He recommended a switch to 5/32" OD/ 1/8" ID tubing for everything because of ease of matching all the parts I'd need to get.  The tap is 1/8-27 NPT.  All the fittings will match the 5/32 OD, and everything with a barb fitting will be 1/8" matching the ID.

I watched Hoss' videos and sketched out how I think this system lays out on paper.  This allowed me to see where I needed threaded fittings and where I needed Tees.  I found a great supplier for these parts online, PolyConn, in Minnesota.  I suppose it's always the trade of lower price per fitting vs a higher price that includes some handling costs, but their prices per fitting were great.  It allowed me to order a good amount of spares.  They were expensive on tubing, so I found a dealer on eBay selling the tubing at a much lower price.  I bought a cheap fuel pump, also from a seller on eBay, figuring I'll be able to address the whole 5/16 fuel pump fitting vs 1/4 (or 5/32) once I got a pump in hand and could measure it. 

Everything arrived over the last few days, and while I could have drilled a couple of holes earlier in the week, this led to me wanting to get to it today.   Earlier in the week, I put the cross slide back on the base, with the gib strip in place, so that I could use the mill as a drill press to drill the vertical hole in the slide, right in the middle of the oil groove.  Then I laid out a square path to find the place to drill on the end of the slide for a fitting, 0.3 down from the top of the slide (non-critical).  The only critical point is that when I drill the 1/8" diameter, 3-1/2" long hole, it has to cross this 1/8" hole. 

I had concluded after that last post on the subject, based on feedback from commenter Raven, that I'd drill a larger diameter hole and only finish out the last inch or so with the 1/8" bit; John suggested I use the recommended tap drill for the larger first hole.  The 1/4" bit I was leaning to was not a special size in any way, so I switched to the recommended R drill (0.339") hole that I'd need for the tap anyway.  I could drill with R, 1/4 and 1/8, but the 1/4 is really not necessary.  That cavity will fill with oil and the only difference is the larger amount of oil in the larger R drill profile.   

The last inch was drilled by hand, and this is it when it was just completed.  The 1/8 bit wanted to flex and move around more than I was comfortable with, so I turned that little piece of aluminum with a 1/8" hole in it to help me keep it centered and not wobbling as much.  Once this was drilled, if everything was cool, I should be able to shine a flashlight in the side hole that this long hole is supposed to intersect with and see light. 

Although this isn't the greatest photo, it shows the 1/8" hole at the end, which was my focus point, and a taper to the larger hole which comes toward you at the top (and goes out of focus).  That taper is the top cut of the R bit. 

I have some more holes to drill and a mess (literally) of chips from cast iron to clean up, but we're moving at a good speed again.