Basic Questions on Singer 99K and Featherweight
 

I own both machines but have not sewn on them yet. Please tell me what needles and bobbins to use/buy for each and if attachments are interchangeable. THX so much!

Both use the same 15x1 system of needles. BUT - 99s go in FLAT to the RIGHT and thread LEFT to RIGHT.
Feathweights go in FLAT to the LEFT and thread RIGHT to LEFT.

99's use Class 66 bobbins. The best ones to buy are the metal ones Sew-Classic sells. Those are some really nice bobbins.
FW's use the 221/301 style bobbins. Also available from Sew-Classic.

You can get the 66s and sometimes the FW bobbins at the big box stores but their quality is hit or miss and I don't recommend them.

Attachments and feet interchange, they are both Low Shank machines.

I strongly suggest you read the owners manuals if you have them, or get them if you don't.

Joe

Joe, thanks ever so much! Will save on a Rolodex card for easy reference till memorized. ;-)

You'll only need to write it down once and maybe reference it twice. If it's not right you won't pick up a stitch at all so you'll learn soon enough! :p (Don't ask me how I know! Lol)

Trivia, I'm sure you're right! :-)

I'll echo Joe and recommend the owner's manual. You can get them from Singer and other places online. You'll get information on machine maintenance, operation, attachments & more.

Need help too
 

I bought a machine at an auction and it has AJ510157 on the model plate which appears to translate to a 99 or a 201 model. I have downloaded the manual and finally got the needle in right and it sews OK. I oiled it in all the places it identifies. But it is really loud! Is that something I should expect or is it possible I have something not set up right? Any ideas?

That serial is for a 66, which is a full-size machine from 1950. ISMACS isn't usually wrong with serial numbers but it's possible. 99s are significantly smaller and lighter than 66s or 201s. 201s thread right to left, the other two left to right, and if you get it wrong the machine won't pick up the bobbin thread.

Did you grease the motor? Does the crank turn easily? Where is the noise originating?
When working on cars I narrow down the source of an unpleasant noise using a length of plastic tubing. Stick one end in your ear and move the other over the machine until the noise is loudest.
In my experience, loose feed dogs and dry motors are likely sources, the former being easier to fix (grease tubes are usually blocked with dried up grease).

Mike, let me add something here. In my experience, after replacing the bobbin and for the initial revolution to bring the bobbin thread up with the needle when the needle is threaded incorrectly, the hook CAN catch “a loop” enabling the bobbin thread to be brought up above the needle plate. It’s when you try to make successive stitches that everything goes to heck in a handbasket....


CD in Oklahoma

You're probably right there: Enough to catch the thread because there's no tension on it.
Threading a needle the wrong way or putting the needle in wrong always ends up in dropped stitches. I usually just end up with a row of perfectly spaced holes (unless I've forgotten to raise the feed dogs, too - it happens) :D