Is my employer being fair with my hours and pay? ANY HELP?

I recently accepted a job that pays commission only at a small automotive shop where there is only one other technician besides the owner.

I'm an automotive technician and have never worked a commission based pay.

My last employer paid me $20/hr for 40hrs a week, plus bonuses.

The owner initially stated that this was a "part time" position, when he called me about the job offer..

The first week I worked I was at the shop for over 40hrs.

After the first week I talked to the owner and said that I did not want to be there but a maximum 40hrs(especially since I don't get overtime pay), but ideally would like to work 25-30hrs..

I feel like the owner and I discussed my issues and concerns several times and came to and understanding before I accepted the job.

I expressed to him that I live 45mins away and don't want to come in to work if there is no work, because unless there is work, I'm just standing around and not making any money, but loosing in gas.

I told him that I would prefer that when there is nothing scheduled for the day, that he let me know, and have me not come in, and told him I am more than willing to be on call in case work comes in that's more than the other tech can handle alone.

So with that said, his basic take on how many hours he expects me to be there vs how many hours I want to be there is "if I don’t want to work, I don’t have to. But if I'm not at work, and work comes in- I'm not going to get it.."

So I'm on my 4th week of work, and I've worked two full days and took a half day today.. I've currently made lower than my states min. wage for the week so far.. (but that’s not my concern I want discussed)

My boss (the owner) is taking this week off for personal family reasons and so it's just me and the other technician. My boss stopped by today and I asked him if i could leave early since it's slow and it was slow the last 2 days, he told me to talk to the other tech. I got it ok'd by the other tech and left after half day. My bossed called me up this evening and yelled at me for leaving because business came in and I wasn't there. I thought there was an understanding that they could call me if work came in that the other tech couldn’t handle.

So with all that said, without my boss directly coming out and saying it I believe he expects and wants me to be there 40 hours a week- 5 days and won’t budge on commission pay only. When I expressed that I don’t want to be there 40 hours when I’m only making commission (especially if I have repeated days like Tuesday where I was there for 8 hours and only made $14 for the day) he tells me that I, just like him, the other technician and the rest of the world—“sometimes have to bite the bullet”… I feel like he’s the owner of a business and should be the only one “biting any bullets” and I am an employee who expects to be paid for any time I give in physically working or expected to work.

I truly believe any of my time is worth money. I put a lot of money and time into my schooling and tools. I don’t ever want to work for a min. wage pay.

What do you think about any of this? Do you think I’m wrong not wanting to be there 40 hours when he’s only willing to pay me commission? If you understand where he’s coming from can you explain to me how he’s being fair- because I can’t seem to understand why I should be making any sacrifices when it’s not my company.

I have to go into work tomorrow and talk to him. The way I’ve been going about talking to him and expressing my issues has not seemed to get through to him. Any pointers on how I should go about it?