Spending money on Bonse Hart Bling-Bling

Not a lot of money.
Not a lot of money.

[ed1: Progress on the Everything SAXS book has been good: a framework is now in place with chapters, the revision ID on the title page and even a Makefile and readme. The time approaches to enter some content!

ed2: Something cool approaches (next week).]

Most of the times we are scrounging for crumbs on the lab floor, sticking parts together with chewing gum and cardboard, but every now and then a small wad of crumpled dollar bills is pushed into ones hand with a hushed whisper: “spend it now!”.

Not a lot of money.
Not a lot of money.

For me, this is a big issue. I was expecting to get a bit of start-up budget at the beginning of the next fiscal year, so I could travel and take time to invest wisely. Unfortunately, I got it now and it needs to be spent quickly. About 20 k$ is now available to be spent on equipment of any sorts or shape (which is not a ridiculous amount of money, but I cannot spend it on people, which is what would really accelerate my research).

Enter the racking of brains: What to spend it on? There are two options; computer equipment and Bonse-Hart instrument components. Computer equipment is easy, we can all use more (redundant!) hard disk space, or an extra screen or two (to further equalise the difference between my desktop size and the size of the top of my desk). The more complicated part is the instrument components.

Soon, we hope to be able to get a new X-ray source to replace the Rigaku 18kW rotating anode which has been the bane of the project. The new X-ray source is going to be cool in more ways than one, requiring a total of no more than 150W to run (meaning that we can run it from a UPS for a few hours as well. Not that we have power issues, but the possibility is there!).

Such a cool source means that the instrument can be running smoothly again, and that I can finally test the new four-bounce crystals. Now that there is money, however, we can take it a step further. One thing is to replace the photon-counting detector (with 50$ counter/ratemeter) with a solid-state X-ray spectrometer for super-low backgrounds. But the most tricky thing to improve is the motions.

So far, most of the instrument components have been manually adjusted. This means that we are optimizing slits by stepwise turning manual stages and checking the X-ray intensity at each point. It works, but is a little time consuming. When you want to motorize, however, there is a balance to be struck between “fast, good and cheap”.

A good and fastest solution is to buy a complete motor stage, for example one of these. However, these stages start at several k$, meaning you can buy two or three of them (and a controller and driver) and be done.

A cheaper, less good and less fast option is to build your own translation stages. You can do this relatively fast by combining a linear ball-screw driven table from THK or SKF with a suitable stepper motor (or stepper motor with integrated driver such as the Trinamic PANDrive or Schneider Lexium). This will shave perhaps 20-50% off of the cost of the previous solution, but requires more time and care in selecting compatible components. Also, performance is not guaranteed.

An even cheaper option (in particular for smaller distances) is to get linear guides (THK or SKF), build a table yourself and attach a linear actuator such as the surprisingly affordable M-228 from PI. Increased flexibility, but you will need to make a suitable base with retaining brackets and mess around with springs.

Stepper motor controllers are another story. Expensive ones are plenty (such as this 5 k$ beauty), but inexpensive is also possible. I use the inexpensive < 100$ Trinamic TMCM-6110, which is excellent (although I would love an ethernet connection).

So I now have to go through quite a bit of this in the remaining 1.5 months, after which all money should be spent. However, I do have one guiding principle when it comes to the BH system: it should be possible to build it on a tight budget. So I am spending money to try things to optimize cost while keeping a decent performance. And maybe, just maybe, make Bonse Hart Ultra-SAXS available to all.

2 Trackbacks / Pingbacks

  1. It is the year that will be (2015 edition). | Looking At Nothing - A SA(X)S Weblog
  2. Plastic Fantastic Project: printing an Ultra-SAXS machine. | Looking At Nothing - A SA(X)S Weblog

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