Science experiment

[mattb]

In some discussion a few days ago, I asked Butch if he cut corner slots using a sabre saw. If so, how did he do it? Turned out he was referring to the outside radius. He used home made guide on his router that cut slots off the outside edge of the track and then by each slot as the guide. Pretty much the way we all do it.

I have always thought about a wide blade in my sabre saw to cut corners free hand. I got a couple blades yesterday and this morning cut the "T" end off one of them and ground the coating off the back edge of the blades. Put them in a vise and used the wire welder to do a couple spots on the back edge of the blade. Kind of ground them smooth at the top 1 inch or so of the new blade and didn't worry with the rest of the edge. This was the result.
P1010002 (1).JPG
P1010004.JPG

It was easy to cut free hand with no wobble in the slot. I have a change in one corner of my track and the curve will be irregular and I think drawing it out and cutting it freehand like this will be much easier then using the router and flexible fence and the saw dust that goes everywhere. If this works out pretty good, it gives the option of turning on the saw and free handing whatever looks good with no setup or tear down.

Obviously there will need to be supports underneath that will keep the tack sections in place when they are cut all the way thru. I can see cutting the slot about half way, screwing a 2X4 underneath that section in 2-3 places then continuing the cut the rest of the way.

[chappyman66]

Matt,
Watching with interest. Should be fine as long as the bracing is frequent enough.
It will be good to see cars run on it though.....

[Pappy]

Matt,

See how an 1/8" axle or drill bit fits into the slot. You'll need exactly 1/8" slot for the router bit to follow that cuts the recess for the braid.

If it fits I think it will work just fine.

[mattb]

The slot as cut is just smaller than 1/8. Without using a mic, I can tell it just needs a bit of sanding to get the full 1/8. As cut, a guide runs thru it very smoothly. I am also wondering if this slot could be touched up with the router and a 1/8 bit. I'll try that to see if the router will run thru this slot without wobbling or cutting and irregular slot. Path of least resistance would be the center of the slot for the bit to run thru.

If you used tape instead of braid, the slot is fine for most any guide. If you want to cut braid reliefs, you will need to open it up slightly. I think the trim router with a 1/8 bit will probably zip right thru it. I will try that and post back.

Possibly a thin piece of steel between the saw blades would spread them enough to be 1/8. Maybe use a different brand of blades.

Science experiment!

[mattb]

Present slot can be re-sized properly by running the 1/8 router bit thru it.. It easily followed the pre-cut slot. But when I wasn't watching it real close the light force from my hands made it cut out of the slot, so it would require really close watching of the cut to make sure you didn't lightly guide it away from the slot.

Using Bosch T slot blades. I'm sure the blades cut slightly wider then they measure. Using a steel ruler, the two blades together measure out appx. 3/32. If you add a third blade you come out around 5/32. If the slot is a bit too wide, the bit cutting the gains may be a little loose and not cut the gains as straight as we want. Probably easiest way to do this is the use 2 blades together and sand a bit(not much) or run the 1/8 router bit thru.

Might be other brands of blades that have a more desirable thickness. Two blades could be welded together with a slight shim to make a nice 1/8 cut. That would be pretty easy to do. Could weld 3 blades together and light grind the outside of one blade to remove1/32. That might be easiest way. You really only use about 1 inch of the blade area to cut. The thickness of the rest doesn't matter.

I will experiment with a 3 blade setup next day or or two.

I am only doing a curve section in a slight remodel of my track. If doing a new track, I would probably rout the slot like always, but maybe a little wider blade would make cutting and following a drawn line on the curves as easy or even easier.

[Pappy]

Matt,

They make a rheostat for routers to slow the RPM down. Maybe that would make it easier to control.

[WB2]

https://www.slotforum.com/forums/index. ... r+%2Bcrest
Post #38 (page 3).

[Wobble]

Your idea seems to me to be a winner. Would it be possible to run a 1/8 HSS drill bit through the slot instead of the router to get the little bit extra width without fear of it travelling off course?

[HomeRacingWorld]

Just a course sandpaper can enlarge the slot quite abit by hand. I always sand to smooth the top edges. Just a thought.

[slothead]

When I built an oval over a decade ago I routed the slots all the way through the 1/4" hardboard surface after gluing it to a ladder type frame made of 1x3's. I did this to prevent debris from ever building up in the slots and it's worked out very well. The cross pieces under the track were about 7" on center and provide plenty of support for the track surface.

In your case using a saber saw to cut the slots you could clamp the frame to the surface and move pieces aside as you go, then put them back in place under the slot and glue in place.

My point is a 2x4 for support will likely be overkill. Good quality pine 1x3's or 1x4's will do. Though, for a few $ more same size PVC molding would be ideal because it will be flat, and never twist, buckle, or splinter. I use it for small projects because it's so reliable.

[mattb]

2X4's make good crossbraces underneath. This is not a table top track. It is a free standing commercial style track. To make the track really stable and solid, the 2X's fasten securely to the track surface and the legs securely to the 2X's. I've tried smaller stuff.

Some more experimentation. I welded two blades together with thin brass washers between them. It measured to 1/8 that way. I cut a nice 1/8 slot and the gain bit cut the gains fine with the trim router. It seemed to not cut as good as the two blades flush together. I think the 1/32 or whatever space between the blades caused it to not cut so easy as the blades flush together did.

The option of welding 3 blades together and grinding the side of one blade or of each side to get down to 1/8 might be another option.

As Harry said, sanding the slot to slight open it to 1/8 would be easy, as I tried it, it didn't take much more sanding then you usually do to smooth the edges of a fresh cut slot. There is still the option of running the router thru the slot with the 1/8 bit. That will require caution and a good eye. Cutting the slot with two blades flush together and then sanding till the 1/8 axle/drill bit slides thru is maybe the best solution.

If you are OK with copper tape, the two blades together offer a great way to freehand cut slots and not make as much mess or require much in the way of tools. This makes building a routed track easy for most anyone with minimal carpenter skills. Taped tracks work just as good as braid, although there are repairs from time to time and maybe you need a second power tap.

On this track remodel, I will use the saw and probably sand the slots a little, then run the router for the gains.

[waaytoomuchintothis]

The cheap plastic spreaders for Bondo that they sell in sets at the car parts stores are perfect for sanding slots. Just wrap a little piece of 150 or 220 grit around it, slip it in the slot, and start rubbing. It goes very fast.

[mattb]

Actually you can fold a piece of 80 grit paper into 3 thickness' and run it thru the slots with no issue. You have to remember there is no bottom in this slot, so the paper doesn't hang up anywhere and goes around a corner as well as the straights.