if i only want to print PLA is there any point in adding a heated bed to my printer build ?
Using PLA on a slightly-heated bed, can actually facilitate removal later, often times making it much easier.
Only glue is needed
A glass heated bed with hairspray will keep anything not shaped like a chopstick sufficiently stuck. And when the bed cools the glass shrinks just enough to break loose from the print and release it easily.
Better question is is it worth adding a heated bed. i would say no. but there is a benifit, but not a $100 benefit … no
I do agree! but make glass holder support heat bed is good ideal
I like to print of slick bare glass with PLA and ~50°C de-greased heated bed. Easy and very clean. But that’s because I already made myself a heated bed… Else I use diluted liquid glue (the puzzle kind with a sponge head - I don’t really like hairspray that sends glue all everywhere)
Absolutely worth it. I print PLA onto plain 2mm glass with a heated bed at 70C.
The glass is cleaned with Pure White Vinegar and the prints adhere well and remove easily.
This has to be the cleanest method, although a little smelly, of preparing a print surface that I have met yet.
Started to experiment with uhu glue and glass heatbed… Adhesion is wonderful, but it’s horribly to remove parts larger than 2-3cm. Blue tape caused corner lifting if your layer heights were off, but was normally easier to remove.
I must be missing the trick.
Need to try clean glass on it’s own.
@Electra_Flarefire you should dilute it, this is why I use thin liquid glue, that I just re-wet over and over with PLA (e.g. check the end of http://www.tridimake.com/2014/01/how-to-3d-print-nylon-and-trimmer-line.html ). It happened to me with too much glue that I remove chips of glass from the bed otherwise (!)
You don’t need any adhesives for PLA + HBP. You can apply kapton tape on glass, then sand the tape to add more surface area. A little Uhu glue has worked well on clean glass @ 70c, with prints more “popping off” as it cools.
@Jeremie_Francois I’ll try watering it down later and see if that helps. And need to try clean glass. My final print surface I hope to be kapton tape on the aluminium heatbed.
Right now it dosen’t ‘pop off’ like @Ben_Van_Den_Broeck suggests, maybe it needs to get below the 25-38c temperatures I have as a minimum. 
Well, kaptop+sanding doesn’t “pop off,” its actually quite aggressive if you tram your printer correctly. Uhu glue deters aggressive adhesion for temp sensitive adhesion. Not sure about aluminum though, always on glass for me.
I use a wood build plate with painters tape.i rarely have issue.
@Camerin_hahn I usually use the same for anything that doesn’t have a large surface area or require exact dimension like most 3d printer parts. A warped axis mount is just asking for trouble.
thanks for all your help guys, i have decided to design my printer so a heating element can easily added later if i have bad results with a cold bed