Crazy variable pricing across line at RS/Farnell - solutions? - Page 1
Forum section: electronics / general

author: bd139
author_rank: Super Contributor
timestamp: November 01, 2017, 09:12:02 am
content: I've noticed a damn annoying thing at Farnell/RS. I'm currently putting together a prototype for something which I intend to actually sell at some point so I'm buying a lot of small volume parts, particularly discretes.So, I'm chucking 10x resistors in at 0.0353 each SSM of 10. That's fine. Suddenly just one flipping value in the same line of parts is a unit cost of 0.145, that's 4.1x the cost for one particular value!?! What's the deal. It's impossible to put together a best price BOM from one vendor's line without hours of digging around. They're all cut tape as well, no different production packaging.What's the deal? Is there any way around this other than bagging 100 of each?Edit: for ref, this is coming out of my pocket rather than an R&D budget so I want to keep costs down.w

author: AndyC_772
author_rank: Super Contributor
timestamp: November 01, 2017, 09:21:14 am
content: I have a simple rule when pricing up boards for volume manufacture:I ignore the cost of generic, small passive components completely.It's not clear from your post whether you're planning to build these boards by hand yourself, or whether you'll be contracting out manufacturing, but either way it's never going to be worth the time trying to get the best price for grit.If, say, an 0603 resistor costs £0.145, more than likely it just means the supplier wants to make £0.141 on each one, probably because it's an odd value. You're paying for snipping a few bits off the reel and sticking them in a labelled bag, not the parts themselves.When you get to volume manufacture, where the cost may actually matter, you'll be buying parts by the reel anyway, and the price will be completely different. More than likely, it'll be vanishingly insignificant compared to the active components, board, enclosure, assembly, testing, approvals, packaging, shipping, and any other overheads you can think of.

author: bd139
author_rank: Super Contributor
timestamp: November 01, 2017, 09:36:54 am
content: Fair points.This is just prototype stage so biting off the cost it is then. Prototype is mainly TH + SMD adapter boards at the moment. I'm just annoyed that small volume pricing is so variable. I'm sticking to E24 values as well so this isn't exactly extended range stuff. I've put about £1700 into it so far in equipment and parts so I shouldn't moan about £1.50 of resistorsI've got a rough ballpark for commercial production already. The enclosure and stock handling are the most expensive parts of the process, followed closely by low volume assembly. Board itself and parts are insignificant really contributing to about 8% of total cost (now I've eliminated some Linear parts). This is product #1 so simply not making a loss and feeling the whole production process out is the main objective.

author: Zero999
author_rank: Super Contributor
timestamp: November 01, 2017, 10:02:28 am
content: Do you often do projects like this?If so, perhaps you should consider investing in an inventory of generic parts? For resistors start with, 0.6W1% metal film, 100 of each E24 values from 10R to 1M, E12 values 1R to 10R and 1M to 10M.That should be sufficient for most projects. Every time the stock runs below 20 for a certain value, order another 100. Avoid buying generic E24 resistors in fewer multiples than 100.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 01, 2017, 10:10:16 am
content: Unless it's something exotic, by the time you need more than a few hundred R's it's often cheaper to buy a reel. It rarely make sense to buy less than 100 resistors.Also worth taking a good look to see if you can minimise the number of BOM lines.For jellybean passives check out Rapid as well.

author: bd139
author_rank: Super Contributor
timestamp: November 01, 2017, 10:20:04 am
content: Requirements are not particularly exotic. I'm going to optimise minimum BOM as well. I've killed a number of resistor values by changing pull ups and impedances/gain in the circuit.This is mostly analogue for reference.I just looked at Rapid and they sell Royal Ohm which is what my dev kit is and I'm running out of. Problem solved - thanks. Had no idea they sold themQuote from: Hero999 on November 01, 2017, 10:02:28 amI don't do this often. This is my first proper venture into production as an individual. I've worked on larger projects before as part of a team.I've got a whole dev kit of 1/4W 1% MF resistors (Royal Ohm). They are running out rapidly which prompted this. mikeselectricstuff just pointed at Rapid which sell 100 off quantities of these.I can actually get most of what I need sourced from Tayda in Thailand (if you look closely at their branded stuff) which is good enough for this task but the turnaround is 2-3 weeks which is too long.