Woodruff Key question

[Stepside]

Are Woodruff keys made tall allow for final fitting? I have one of the kits with 10 keys of each of a dozen sizes. Might be sub-standard quality.

I used a new Key cutter for the key seat. The broach is a new DuMont broach. The fit of the shaft and mating part is very good. the key seat depth is within the tolerance from Machinerys Handbook.

A bit of work with a file and everything fits. The question is more of being curious as the job is finished.

Thanks for any and all information.

Pete

[rkepler]

Not that I know of, but you could mic the key and see if it's in spec. Could be that the hole is on the light side, the key is on the heavy side and the keyway is a little light - all adding up to needing a lick of the file to fit.

Also - might check to see that the key isn't tilted even a little bit?

[Toolguy]

Ideally, the key will be a slight press fit in the shaft so there is no movement between the 2 parts. The keyseat cutters are normally made to pretty close tolerances in terms of thickness, and slightly oversized on diameter to make sure a Woodruff key will seat to the bottom and to allow for a couple of sharpenings. The keys themselves are not usually a close tolerance item, and sometimes a little oversize to allow for fitting or a worn keyway.

[Illinoyance]

A key needs to be a tight it in both the shaft and the hub. When the shaft direction reverses any gap between the key and the keyway will eventually beat out the keyways to the point there is considerable motion in the keyed connection.

[10KPete]

A key needs o be a tight it in both the shaft and the hub. When the shaft direction reverses any gap between the key and the keyway will eventually brat out the keyways to the point there is considerable motion in the keyed connection.

How many keyseats have I had to re-cut 'cause the first guy didn't get it tight enough????

Way too many...

Pete

[Stepside]

Tight is not the issue. They fit snug or better width wise in both the shaft and the mating part, The issue is/was height and I wondered if that was on purpose or poor tolerance of the keys. I have seen key stock the is oversize to allow for a "file fit" in worn keyways.

[J Tiers]

perhaps oversize to allow for poor fit, or wear of the key slots, in mating parts... gears, pulleys, levers, etc.

[projectnut]

Woodruff keys come in two standard profiles, flat bottom and round bottom. The smaller keys (below 1/2") come in either profile. Those over 1/2" are generally the flat bottom profile. They also come in different diameters. For instance an 1/8" wide key comes in two different styles which means two different heights and two different diameters. A number 3 key is 1/8" wide, 1/2" in diameter, and .194" in height. A number 5 key is 1/8" wide, 5/8" in diameter, and .240" tall. Check your keyway cutter to be sure the number on the shank matches the number of the key you are trying to install.

[Stepside]

The key size and the cutter match. The fit is excellent except for being too tall. All numbers from Machinery's Handbook. My question was "are the keys tall on purpose for a file fit or are they poor quality off size?".

Thanks for all the replies.

Pete

[boslab]

Invented by WN woodruff in 1888, he got a Franklin medal too!, I don't think I've ever had one that didn't need a bit of fettling, too loose is the sin, just a bit of movement is all it needs to wear out the hole or key.
Mark

[Arcane]

Stepside, where are you measuring your depth of cut from? The top of the shaft or the side of the slot?

[projectnut]

The key size and the cutter match. The fit is excellent except for being too tall. All numbers from Machinery's Handbook. My question was "are the keys tall on purpose for a file fit or are they poor quality off size?".

Thanks for all the replies.

Pete

The short answer is no IF the key is from a reputable manufacturer. I have cut and replaced hundreds if not thousands over the years. The only keys I've had to file down were cheapies from off shore manufacturers. The last assortment I purchased was from McMaster. They were made in Taiwan. So far I've used about a dozen of them and none have had to be modified to fit new or existing key slots.

They are generally not hardened, so it is possible they could get a ding or burr on a corner making them hard to fit. Sometimes they require the stroke or two of a file to remove the burr. I've not yet had any that are too tall.

[Stepside]

Arcane

You might be on to something. I touched off on the shaft and raised the table the depth in the handbook.

Pete

[Illinoyance]

Arcane

You might be on to something. I touched off on the shaft and raised the table the depth in the handbook.

Pete

Feed the cutter until it cuts the full width of the cutter then feed to the depth shown in the handbook.

[Stepside]

In the next few days I will make a sample using the technique put forth by Illinoyance.

thanks for the tip.

Pete