Groovy

[Hyperion98]

I'm using tongue and groove and I want to know whether 0.01 mm difference in size on both sides of the tongue between the tongue and groove will mean to the fitting.

I want the contact to be as close as possible while still being able to remove the tongued item by hand.

The material is aluminium.

 

[unclesyd]

That is pretty tight call-out for Al.
A couple of questions.
What is the configuration straight, curved, or what?
Are you going to assemble this with lubricant?
How ridged is the machine that machines the two parts?
How ridged are to the two components?

 

[Hyperion98]

The tongue and groove are straight.
No lubricant will be used.
The machine I take it is very rigid (it's a 3 axis mill machine)
The two components are very ridged. It's 30mm thick on one and part and 60mm.

 

[BillPSU]

How long is the fit 1" or 24"? How are you going to cut the tongue and groove?
Are you going to make the groove .000/+.005 and the tongue -.005/.000 from nominal?
I do not believe you can make parts of that tolerance unless you take many special precautions such as temperature control and special measuring devices.
Now if you want a single part to just fit make the smaller part first and use it as a go gage on the larger part. Caution aluminum on aluminum will gall. If thes tongue and groove fit is disassembled and reassembled many times I would recommend you use dissimilar metals in the tongue and grrove.
A more achievable tolerance on a production basis is .00/+.02mm groove and -.02/.00mm tongue.
DIN tolerance of h7 and H7 through h9 and H9 would be the approximate callout depending on the key width.

 

[unclesyd]

As stated by DillPSU this will be very hard to accomplish. You could probably make an .02 mm tolerance with very careful setup and very sharp fast spindle speeds on the tooling.

Comeback with the exact dimensions of the tongue and groove if you can.
What is the Al alloy?

 

[Hyperion98]

Thanks for the input. I don't have access to the machine I just send drawing over the internet to a machine shop.
So we can assume only average spindle speeds and average sharpness on the tooling.

At present the groove is 10.160 mm and the tongue is 10.158 mm i.e. one hundreth smaller on both sides. (or -01/.00mm have I got the terminology right?)

Shall I just make the tongue .04 smaller?

I looked up "gall" I don't know what it means in the engineering sense, but I can imagine what it means from the Google definition. It cuts and wears. I didn't think of that.

 

[JDana]

Galling of aluminum is when bits of metal from one part stick to the other part from friction and/or heat. The softer the alloy/ heat treat the more galling occurrs.

 

[Hyperion98]

Sorry to ask again, but any on ewith experience out there - I need your assistance. Assuming average spindle speed and blade sharpness, how much smaller shall I make my tongue to fit the groove?

0.04mm?

 

[Hyperion98]

I am now using carbon grade steel.

 

[Tmoose]

"At present the groove is 10.160 mm and the tongue is 10.158 mm i.e. one hundreth smaller on both sides. (or -01/.00mm).
.
If those are still your dimensions then you could expect to get a groove 10.150 and a tongue 10.158 . That would be an interference fit. Then, Sometimes you might get a 10.160 groove and a 10.148 tongue which would be ~ a sliding fit with barely cetectable looseness.

Achieving location accuracy <0.012 mm via fits is tough. Selective fits or expensive parts are probably required.
I Might think about using commercial dowels in a hole and a slot where I can "buy" precision for fairly short dollars.