Month: October 2006

A new spindle for our Opti CNC mill

Jari has been busy planning and building a new spindle for our CNC mill. The project is now about half-way so I thought I'd take a few pictures and write some text.

So far we've been using the stock spindle on the Opti BF20 which has a Morse Taper #2. The original motor burned out at some point so we had to replace it. But as our machine has run for probably hundreds of hours already the bearings are showing some serious wear. We measured a runout of more than 0.05 mm...

On the left the new spindle, Morse Taper #3, from littlemachineshop, a bargain at $34.95 !. It's sold as a lathe spindle, but we thought we'd get the longest spindle they have to place the bearings as far apart as possible for rigidity.

This is part of a larger upgrade plan for the mill which will include replacing the dovetail ways of the stock mill with linear bearings, replacing the standard acme screws with ballscews, and upgrading the control electronics to use AC servos.

The linear bearings are 15mm wide and manufactured by IKO. We got the ballscews from metallstore (I think they are made by HiWin), and the Sanyo AC servos are from last years surpluscenter sellout of Sanyo AC servos. Three 400 W servos will direct-drive the ballscrews (I hope the torque will be more than enough, otherwise we will have to resort to gearing as is often done with servos). A 1 kW servo will be used as the spindle motor. I'm hoping that using a servo as the spindle motor will allow rigid-tapping eventually. Finding affordable servodrives for the AC motors (sinusoidal 3-phase commutation based on hall sensors and/or 2000 ppr encoder) is not easy, so I've actually had a go at building my own drive (also check out Tero Kontkanens effort).

Everything will be controlled by EMC, with a Mesa Electronics M5I20 PCI-card for I/O.

Some pictures of the spindle assembly and toolholders below...

Continue reading A new spindle for our Opti CNC mill

More 2.4 GHz radios and modules

Predictably, more and more RC-manufacturers are introducing "crystal-less" 2.4 GHz remote control systems.

Spektrum has come out with a new 7-channel system called the DX7. It's not on their website yet, but Horizon hobby has it for sale. This one is supposed to be a radio for 'real' models, not only meant for park-flyers like the DX6. I wonder if there will be a problem with 'CE' approval with regards to the output power - A rumor I heard was that the 'CE' marked version of the DX6 has a reduced output power compared to the US model ??

There's also a new player on the market, Xtreme Power Systems, which will introduce their new xtremelink module+rx combo shortly. They too promise increased range and reliability. In contrast to Spektrum, who talk about either 40 or 80 simultaneous working modules, Xtremelink claims up to 390 000 simultaneous active modules ! Also, up to 1 mile ground based range. Pricing and deliverytime still open.

The Futaba modules I noticed back in January were on display at Model Expo in the spring but the local agent said it would take some time before they come to market. I've detected no activity in the Futaba camp so far...

For the new boat, I've bought myself a DX6. Naturally I'm going to mod it a bit before use ;). I've ordered a switched-mode regulator which supposedly will reduce the current drain of the Tx a lot. Also, I've gotten very used to the 'no antenna' look and feel of the Futaba 3VCS with a Spektrum module (especially usefull when it rains, the whole radio goes inside the Tx-cover, no leaking hole for antenna needed). But the stock DX6 has an antenna that sticks out :(. Cell-phones have had internal antennas for years and nobody buys phones with external antennas anymore - so the DX6 antenna needs to go inside the case too ! I'll report later how that goes...

Nordic Cup 3, Saltsjöbaden

This weekend I took part in the final Nordic Cup race of the year, in Saltsjöbaden just south of Stockholm. 28 competitors showed up and we sailed 9 races on Saturday and about 5-6? more on Sunday. Saturday was a very wet day with light to heavy rain the whole day. We started in no2 rig and switched to no1 for the later races. Sunday saw the wind coming from an unfortunate direction over a hill with wild shifts and gusts as a result - frustrating racing at times...

Nothing new under the sun when it comes to the results, Torvald Klem won, 2 points in front of Sören Andresen, and myself third, 2 points after Sören.

No pictures from this event as Saturday was too wet for photography and I tried my best to concetrate on the sailing on Sunday... If anyone has photos, please send me them and I'll gladly post them!

Results and pictures are likely to appear on www.iom-nordic.org in a few days.