It's completely down to your DM what check is appropriate to make you attempt, but RAW you'd make a check using either a skill or a tool, not both. Either way, it's 1d20 plus the appropriate ability modifier plus proficiency if you have it. If you are proficient in one but not the other, you may want to describe your character performing the task in a particular way which leans on their strengths.
If you use the thieves' tools, it'd likely be a check of 1d20 + Dexmod + 3 (assuming proficiency in thieves' tools)
If you rely on pure manual trickery, it'd be 1d20 + Dexmod + 3 (assuming proficiency in Sleight of Hand)
If you're a level 6+ artificer then you have expertise in any tool that you have proficiency in, so you'd replace the +3 from the tool option with a +6.
Having expertise doubles the proficiency bonus, it does not change your ability modifier. However, can you confirm your character's dexterity modifier? Your initial post implied that they were proficient in Sleight of Hand but only had +4 total for the skill, which means that your Dex mod is only +1. In contrast, your 2nd post states that they have a Dex mod of +4, meaning a Dexterity ability score of either 18 or 19. (seems very high for a low level artificer)
Can someone please explain to me how this works?
Base proficiency = 3
skill proficient for slight of hand is +4
To my understanding if I use thieves tools and with the skill slight of hand to unlock a door.
I would roll a d20 add it to the skill and add my proficiency onto it again as well. Correct?
It's completely down to your DM what check is appropriate to make you attempt, but RAW you'd make a check using either a skill or a tool, not both. Either way, it's 1d20 plus the appropriate ability modifier plus proficiency if you have it. If you are proficient in one but not the other, you may want to describe your character performing the task in a particular way which leans on their strengths.
If you use the thieves' tools, it'd likely be a check of 1d20 + Dexmod + 3 (assuming proficiency in thieves' tools)
If you rely on pure manual trickery, it'd be 1d20 + Dexmod + 3 (assuming proficiency in Sleight of Hand)
If you're a level 6+ artificer then you have expertise in any tool that you have proficiency in, so you'd replace the +3 from the tool option with a +6.
OK so going off your example - lets say that I am proficient in thieves tools.
So 1d20+dex mod(+4) + proficieny (+3) = 1d20 + 7?
then being a level 6 artificier it would be 1d20 +7 + 3?
not trying to be dumb, just trying to understand. Or would not get the ability mod and just go off of Proficiency?
With proficiency: 1d20 + 4 (Dexmod) + 3 (proficiency) = 1d20 + 7
With expertise: 1d20 + 4 (Dexmod) + 6 (proficiency) = 1d20 + 10
Having expertise doubles the proficiency bonus, it does not change your ability modifier. However, can you confirm your character's dexterity modifier? Your initial post implied that they were proficient in Sleight of Hand but only had +4 total for the skill, which means that your Dex mod is only +1. In contrast, your 2nd post states that they have a Dex mod of +4, meaning a Dexterity ability score of either 18 or 19. (seems very high for a low level artificer)
Yeah I am sorry.
It is a +1 and my proficiency is a +3
7th lvl artificer.
Then you would have a total of 1d20 + 1 (Dexmod) + 6 (Expertise in thieves' tools) = 1d20 + 7.
Sweet that is what I thought. Thank you.
No. If you're unlocking a door, you use ONLY your Thieves' Tools proficiency.
Which attribute to use with them is up to your GM, but typically that will be Dexterity.