Floats

**BobL** · 10th February 2008, 12:46 AM

I had a bit of a go at cutting some float teeth with the mill at work.

My O1 tool steel is 1" wide x 5/32 (4mm) thick x 37" long.

I bought two cutters - this big mutha! 3" diameter 60º cutter. Unfortunately the cutter teeth are not pointy enough and the gullets on the float teeth it cuts would need to be cleaned out with a file - and it needs to be operated with the mill head tilted over at 50º - I don't really know why but I don't like doing that - maybe it has something to do with the lube oil that pours out from the mill head when I do that.

Bigcutter.jpg
In this picture you can see where unwanted contact was being made.
Picture-6.jpg
The other cutter was a 60º dovetail, it can be operated to make the right teeth profile with the mill head tilted at 20º.
Anyway, it certainly works s you can see below.

Teeth space is 3 mm or about 8 TPI. It helps having a digital positioning readout on the mill to get the teeth spacing even.

Teeth Depth are 1.15 mm with an 80º tooth angle.
DovetailandTeeth.jpg

Here is a cutting action shot. I probably didn't need to use that much lube but it doesn't hurt - it just makes a mess all over the place.
cuttingaction.jpg

First complete float blade.
firstshot.jpg

All done
cutfloats.jpg

Some technical details for Kevin.

The milling was obviously much easier to do as something like 3 x 0.4 mm passes because you could then basically feed the in-out table almost as fast as you could crank it but then the 80º rake would not be formed so each tooth has to be made in one pass. The feed rate I felt most comfortable with was about 50 seconds for the complete pass (although I could do it in 30 I did not feel like pushing it.) Add 10 seconds to reposition the cross feed tabled for the next tooth and it was about 1 min per tooth. So 150 mm of teeth or 50 teeth took about an hour including set up and clean up.

A couple of other points.
- I held the blank blades in a vice. For the side or cheek floats which are triangular it would be tempting to cut the shape out first to have less teeth length to cut but holding a triangular shape in a vice will be a pig so you have to cut the full teeth lengths OR work out another way to hold down the blanks.
- to make sure I had an real edge on each tooth I cut the base of each tooth to 1.20 mm deep. Due to the overlapping effects of the various angles, each tooth still came out at 1.15 mm high but recessed by 0.05 mm below the original top of the blank.
teethsides.jpg

The 60º dovetail cutter is from McJing and worked really well for 2.5 floats. The only way I had of holding it in the mill was a Morse tapered chuck which is really not an ideal holding mechanism for any side force cutting. When pushing it a bit much the chuck and bit fell out of the MT and chipped a couple of the cutter teeth and it needs a resharpen. I would suggest getting a proper threaded dovetail milling cutter so you don't need to so this. Fortunately the only float teeth it mangled while doing this are on the side of the side float and those bits are going to be be cut away from the side float blank due to its triangular shape.

Oh yeah and I worked out how to get 5 floats out of a 37" length of tool steel but two of them have to be edge floats, and the cheek float is a little shorter than the other 4 but that's how it should be anyway.It doesn't help all that much because you really only need one edge float.
set.jpg

**kevjed** · 10th February 2008, 06:29 PM

Thanks for the post and feed back Bob.
Great photo's, it makes it clear how you've gone about things. Buggar about the chuck and cutter falling out. Also a bummer about the big mutha cutter not having enough point on the ends. I was hoping that I would order one this week but I may have to re think that now and go for the 60º dovetail cutter. Do you think that the hand work to clean up the gullets would be over the top? Would you happen to have a photo of the cut made by this tool please? I just figure that the bigger cutter should stand up to extended use a little better.
I notice that you have made push floats. Are you going to make pull floats as well, or a least one of the edge floats as a pull?
I looking forward to seeing the finished product soon.
I will place on order for the cutter very soon and hope that I too will be able to post a few pics of the finished product down the track.
Well done.
Kevin

**scooter** · 10th February 2008, 09:36 PM

Great post, Bob.

**thumbsucker** · 10th February 2008, 09:40 PM

Great Job Bob

I look forward to see what Kevjed comes up with.

My fingers are crossed. As it may save me from filling my floats by hand.

**BobL** · 10th February 2008, 10:25 PM

Thanks All for the feedback.

Originally Posted by kevjed

Do you think that the hand work to clean up the gullets would be over the top?

No, I don't think it would too much to clean up. I guess it depends how clean and sharp a gullet you think would be appropriate and how sharp the 60º angles on a triangular file you could lay your hands on.

Originally Posted by kevjed

Would you happen to have a photo of the cut made by this tool please?

Another reason I did not pursue the big cutter was my setup ran into trouble with the length of arbor extending out from the end. Basically it was not allowing me to cut the teeth deep enough - see picture.

I can probably just grind a mm off the arbor ends but didn't want to do that without checking with the chief techo at work. I did some testing on a end of a bit of scrap mild steel at work so the piece should be out there somewhere. I am actually in Melbourne right now - I flew in this evening - so it will have to wait till I get back on Thursday.

Originally Posted by kevjed

I just figure that the bigger cutter should stand up to extended use a little better.

Yep agree, basically for the same $ there are many more points on the big cutter so if one gets a little chip or dull it should not be so bad.

Originally Posted by kevjed

I notice that you have made push floats. Are you going to make pull floats as well, or a least one of the edge floats as a pull?

Yes I will make some pull floats as well. Certainly one of the edge ones will be pull. Now that I have the system worked out I also want to make some in
different thicknesses. I have no more 5/32" thick O1 left, I have some 3/16" but need to get hold of some 1/8" to make a side and cheek pull floats.

**m2c1Iw** · 10th February 2008, 10:43 PM

Hi Bob,

The recess of the teeth from the milling got me wondering about my LN float, something I hadn't noticed before is that the teeth are proud of the stock by the tooth depth (not very observant of me). In other words the handle section is 3.75mm and teeth section is 4.78mm.

How would LN achieve this surely they don't mill the bar down for the handle section. I had assumed they stamp the teeth then dress but seeing this thread perhaps they machine the teeth, the different thickness is intriguing. You can tell I'm not a toolmaker

Mike

**BobL** · 10th February 2008, 11:18 PM

Originally Posted by m2c1Iw

The recess of the teeth from the milling got me wondering about my LN float, something I hadn't noticed before is that the teeth are proud of the stock by the tooth depth (not very observant of me). In other words the handle section is 3.75mm and teeth section is 4.78mm.

How would LN achieve this surely they don't mill the bar down for the handle section. I had assumed they stamp the teeth then dress but seeing this thread perhaps they machine the teeth, the different thickness is intriguing. You can tell I'm not a toolmaker

Mike

I dunno how they make them. Having the teeth proud would lighten the tool and looks better - I don't think it does anything special for function? Wait - not having it proud will reduce the "bite" that the flat can make if the handle is riding anywhere on the timber as well.

OTOH while it makes sense doing this for the 3/16" thick floats (which your is) but I doubt they do it for a 1/8" float or it would be too thin. Do you have one and if so can you check it?

Bob

**m2c1Iw** · 10th February 2008, 11:21 PM

Only have the 3/16 Bob, I have had a look at the others but I'm afraid I did not take note of any difference in thickness.

**BobL** · 11th February 2008, 12:26 AM

I read up a bit about sharpening floats etc on the web and I think I have worked out why they do it - it is because it makes the teeth easier to joint .

Obviously the top one with the teeth proud will be easier to joint. To make the teeth proud will not be too hard with a mill or surface grinder and it clearly does not need to be done where the blade goes under the handle. Even a 12 mm wide slot or recess will be sufficient.

I also discovered the importance of the "first tooth" see top. Apparently it's critical to the successful operation of the float. But it does not need to be cut with the mill it can be shaped with a grinder.

**wheelinround** · 11th February 2008, 09:52 AM

top job Bob look great

thanks for sharing

**kevjed** · 11th February 2008, 07:22 PM

Thanks once again Bob. I'll just mull over all of this for another day or two before I commit to buying the cutters. It may be worth getting both?
I'm not sure why you got the large cutter with 30º either side (60º included)? (or is that just in the diagram?hard to tell in the photo of the bigcutter) I would have thought they had a large cutter much like the dovetail cutter, flat on one side and 60º included? I will investigate a little more.
Great work

**BobL** · 11th February 2008, 11:01 PM

Originally Posted by kevjed

Thanks once again Bob. I'll just mull over all of this for another day or two before I commit to buying the cutters. It may be worth getting both?
I'm not sure why you got the large cutter with 30º either side (60º included)? (or is that just in the diagram?hard to tell in the photo of the bigcutter) I would have thought they had a large cutter much like the dovetail cutter, flat on one side and 60º included? I will investigate a little more.
Great work

Yes the large cutter has the 30º either side.

Some givens are
- the angle of the tooth rake should be 80º
- the TPI should be about 8 (3.175 mm).
This means
- if the gullet angle is 60º the depth of the gullet will be 1.15 mm
- if the gullet angle is 45º the depth of the gullet will be 2.23 mm

A 1.15 mm depth works well for a 1/8" (3.175 mm) thick float
A 2.23 mm deep gullet would be too much for a 1/8" thick float and probably still too much for a 5/32" (3.97 mm) thick float but OK for a 3/16" (4.78 mm) thick float.

That's why I figured a 60 degree cutter would be about right for a 5/32 thick blade.

The dovetail cutter I ued was a 3/4" diameter 60º angle cutter. You could go for something like a 1" diameter but the McJing one does not have anymore teeth and the same amount of tooth is going to be be used whether its 3/4 or 1". It will give a higher cutting speed for the same RPM.

I will try the big cutter again once I sort out my arbor issues.

Bob

**BobL** · 17th February 2008, 10:42 PM

Just a brief update on the floats project.

Today I milled a 1.2 mm deep x 15 mm wide relief in the blades between the end of the teeth and where the handle starts. This will make the teeth easier to joint later in their lifetimes.
Jointing.jpg
I then cut them out to shape and ground the sides so they were symmetrical. I still haven't cut the teeth on the edge floats. I used the little triangular bits left over from the side float to make cool little mini floats?
Minifloats.jpg

KevJed, You asked about the teeth cut with the big cutter? Well I managed to find the piece of steel I used to try out the big cutter and you can see the result in the picture below. The teeth, especially the gullets are nowhere near as well defined as those made by the dovetail cutter. It would take a fair bit of filing to get them even close to the same definition as the dovetail cut teeth.

Bigcutterteeth.jpg

The next steps are to make the handles and fit them all up - then take them apart, a final sharpen of the teeth and then harden and temper the blades.

Cheers

**Waldo** · 20th February 2008, 09:18 AM

G'day BobL,

What a great read. There's a lot to be said for working with a tool of quality, but even more to be said about a tool of quality that you've made yourself.

**BobL** · 20th February 2008, 11:50 PM

Originally Posted by Waldo

G'day BobL,
What a great read. There's a lot to be said for working with a tool of quality, but even more to be said about a tool of quality that you've made yourself.

Thanks Waldo, I've finished cutting the teeth on the edge floats so now its - HANDLE TIME! Then I have to take then all apart and harden and temper then blades.

Will post something when I have made some progress.

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