Drilling holes for Cannon and Co fans

[digitalfreight]

Pictured below is one of those projects I want to accomplish in a short time, with limited expense, but not be horrified when it rolls by on the layout. This is going to be a patch job CNW SD-45 that they purchased from Conrail. This particular unit (the 6535) was never painted into CNW colors.



Going cheap, I picked up a Bachman SD45. At first I was only going to add a few details and then smudge up the paint. But, I could not stand the fans. I believe roof tops are the most important detailing aspect since from our perspective it's typically what we see. However, after purchasing the Cannon fans for replacement, another daunting challenge faced me. How could I accurately drill out the fan mount holes, particularly with their fan detail already in the way?

I paid close attention to Brian Banna's info (http://www.6axlepwr.com/HOOD_SIDES_7.html) on making accurate holes, but was afraid that my patience and skill would run out. Instead, I came up with the following: Cannon commends a .563" - .585" hole for gap free mounting of the fan base. This translates very nicely to a 9/16" hole (.563"), but the thought of running my 9/16" drill bit through the top of this fragile shell wasn't very appealing. Then I remembered my step drill. Purchased on sale for less than $5 at Harbor Freight (see www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44460). This item proved to be the ideal method for drilling very precise holes.



Ideally I would have had a variable speed drill press at my disposal. But, lacking that, I got out my cordless drill, put it on slow, and pressed on. In short, it worked amazing! The steps of the drill allow you to gradually increase the size of the hole, all the while checking for center. The second to last step gives you a great idea of how close you are to center, allowing you to adjust a bit side to side for the final cut. Each hole came out flawlessly.



The only minor drawback was that if you're working on some shell with pre-formed fans there will still be a slight ridge around the edge of your hole if they are not preformed to the proper size. In this case I had to take a little knife and sandpaper to the remaining edge to get a flush fit. The beauty of the process is that it maintained the integrity of the factory paint and form so that I can still get by without doing the full detailing works. Thanks Brian B. for motivating me to do a little more and making me think of ways to get it done! Mike

[sd50f]

That's a nice trick! I did the shell drilling thing about three weeks ago. I used a 1/4" bit in my Ryobi cordless to make a pilot hole, and then enlarged it using Dremel grinders and sanders. Once I had it close, I used my X-Acto knife to trim them to the right shape. Not fun. I'll have to get one of these bits.

timothy dineen

[diesel]

I use a similar method. I drill a pilot hole with a small drill in the center of the fan first. Then I use a cone shaped grinding stone to open the hole to the fan housing. I use a spru nipper to cut away the old housing, then open the hole with the stone the rest of the way, then clean up with a chisel blade as well. It takes some doing, but I don't dislike it the way I feel about cutting through zamack... uuhhhhgggg

[mosteam3985]

and not be horrified as it rolls by on the layout [/qoute]

O My Gosh I laughed so hard when I read that!! ;D ;D ;D

[beentherecnthat]

Another tool which I have is a hand reamer. Once you have a 1/8" pilot hole, the reamer is used to open it up to 1/2" which is just a little less than a fan requires. Sanding finishes the opening. The reamer was less than $10 and any step drills I have seen are at leas $25.

[stewarttrains98]

That is a great tip on how to drill out the fans. I have tried a few ways and they worked but was a PITA. I have to get that tool, too bad I don't have a drill press and will have to use the same drill trick you used.

[sd45longhoodfoward]

this is and older but always news worthy post i to had learn the hard way at first on the cannon fans i also now use precision scale co brass fan housing casting the are pretty neat!!and i also use Plano fans they are photo etched stainles steel to put in the precesion scale brass fan housings/i have installed them and cut out the brass grills and in stalled Plano grills wich look pretty darn cool also!

[steve4]

I'm new into H0 scale fans so I made this tool to drill the holes out. it has the exact diameter for the Cannon fans on SD40-2s (haven't done any others yet). it's made out of a wood drill and a handle from a file. it's easy to use, first I drill a hole big enough for the tip of the fan-tool and then the fan-tool does gently the rest. no dremel or bigger electric drill needed...



edit: I use the fan-tool from the inside and the fans will just pop off when the drill gets thru the shell

[dcs077]

i myself have a set of cone cutters which are like the step drill but are completely tapered. i find with these you are not limited to the graduations of the step drill and if you come up a little on the small side you can drill just a little more for the perfect size.

Dan

[m a y o r 79]

The spade bit is a good idea. I'm always nervous about using a bit in a drill to open up fan holes, even on a slow speed setting if you slip a little you can easily ruin the shell. I usually opt for hand powered tools for somethign like that, and a lot of sanding and dry fitting parts when you're getting close.

I'll have to give the spade bit a try, looks like a neat idea.

[icghogger]

Excellent Idea, Steve, thanks for sharing!!

[Randy Earle]

Now that's callin a spade a spade guys. ;D

[sd45longhoodfoward]

GOOD IDEA!also used a cone shaped reamer that seemed to work well this time around and harbor freight has the 3 PC step drill set for 14.95 i looked it up@ HF i went Thur my grandfathers tools he had along with his engineering skills he was helluva tool and die maker!
the coned shaped reamer worked great ! just do try to cut the holes to exact size use the outer ring wall of the fan you cut off to be a some what close guide the hole is angled to the inside of the shell and just hit it a bit with an axcto knife and yer in da biz!!!!!

[e86900]

I just received a sale flyer from Harbor Freight, and they have a three piece stepdrill set on sale for $8.98, regular price $14.99. Add says you can drill 28 different hole sizes. Sale runs through June 30th.

Eddie

[John]

I bought a step drill a few months ago, its a fantastic tool and perfect for making holes for cannon fans.
I have found that I can simply twist the bit by hand, the plastic shells are not hard to cut and you also get a lot more control over the cut. There are some very good prices on ebay.