Why didn't I go with the Tapmatic? The needed collet won't be here for another week or so. Jittery impatience, that's why.
Good for you taking on the build. Looks great so far. I'm about 90% done a 5 cylinder radial, glow ignition. Also my first engine & was in deep over my head. But it's coming together & has been very rewarding.
There are a few things to pay attention to on your Tapmatic regarding blind holes.
- there is a calculation that determines what offset distance to set your your depth stop above where you want the tap to terminate. The reason is the mechanism will allow the tap to propagate further into hole even with no down feed, beyond the depth it appear when 'un-sprung'. What this means is, without correct depth stop, its amazingly easy to firmly spud the tap into the bottom of hole & break it. Ask me how I know. And yes it was a crankcase on the proverbial second last hole.
- Similarly pay attention to the over-hole distance. The plans may call for something shallower (ie. presuming hand tapping) that may require adjustments. So get real familiar with the unit beforehand on same material & hole conditions. A lower clutch setting may save you a break. A Tapmatic will allow you to chase an existing threaded hole no problem. Its really quite ingenious. But if you do, blow any the chips out. Always.
- get high quality new taps that eject chips outward not downward. Avoid using them on steel or other materials if you can. Its a bad area to try & save a few bucks if you value your time remaking complicated parts
- there is no miracle cutting fluid IMO. I find WD-40 works about the same as the dedicated aluminum products, its just a matter of how flushed my skin becomes after inhaling the stuff. I prefer a tapping cream I got from KBC. It seems to have less resistance & chips stick less, but always start each hole with a clean, brushed clean tap.
- all said, you have probably seen or already using these manual mode tapping aids. Sometimes if the hole positioning is the time consuming effort, its just as quick to pop it in after drilling right then & there while everything is aligned. The Tapmatic setup only makes sense if you can do a run of a bunch of holes IMO. The slender tommy bar style is mine. The knurled wheel adapters have been favored by model engineering types for a long time
Peter