Expressing hard work with idioms

Question

Consider the situation where I am handling a project, and now my manager assigns me one more.
So I want to express to him that it will be hard work. I am in software, so taking on two projects will require more hours of sitting.

I thought of the following ways to express it:

1. With the two projects, I will be burning candles at both ends
2. With the two projects, I will have my nose to the grindstone.

I am trying to use idioms here. Are they correct usage?

Any other way to express the same with impactful words

Answer 1

The first idiom is correctly "burning the candle at both ends". (It is never used with the plural "candles".) The original metaphor was lighting a candle at both the top and the bottom, so that it gave more light, and more work could be done, but only for a shorter time because the candle would burn up twice as fast. In modern use, this idiom suggests not so much working harder as working longer hours, "pulling all-nighters" with the further implication that this us possible only for a limited time. That may not be quite the meaning you want here.

Your second idiom "nose to the grindstone" fits the situation described naturally, and needs no adjustment.

A possible third idiom would be:

3. With the two projects, I will be working my fingers to the bone.

This suggests that the speaker is being over-worked.

A possible fourth idiom would be:

4. With the two projects, I will be going at full throttle.

This suggests that the speaker will be working at the maximum possible pace, but does not imply that the pace cannot be sustained.