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  1. #31
    Rich's Avatar
    Lives in Warrington, United Kingdom. Last Activity: 08-04-2015 Has been a member for 5-6 years. Has a total post count of 30. Received thanks 1 times, giving thanks to others 0 times.
    Been a while.

    The table is finished - top need a final coat of urethane. The internal section of the table was coated with an urethane, grout like in its consistency, and has dampened the vibration. I haven't measured the frequency response - but visually I'm happy. The table was built with three internal vacuum boxes. They work, but I messed up the table top. When it came to the final construction, it tuned out that I'd not thought through or simply measured properly the height of the sections I was using. At the last minute I changed my approach and made matter worse than they need to be. I can fix the residual issue - its just annoying to have to fix the issue.

    The table slides over a wooden bench and locks tightly into place. Its bloody heavy and a little clumsy - so a couple of height adjustable wheels are required to make this a little more practical. They will aid the lifting of the table when the front end is moving over the side ramps. Its set up so when table drops into place it meets its mark and all the feet then touch the floor. The addition of the extra weight of the gantry has just made the lifting of the table tricky - no place to grip at the right height for lifting.

    Once its over the bench its becomes a solid unit - aided by a couple of clips and jams.

    The machine has come together. Everything in place except the leadscrew - just need to get that on a lathe. The belts and pulleys have been fitted - the belt has yet to be bonded into place. Various threaded holes in plate aluminium have been re-enforced with backing nuts. I've yet to add any thread lock. Flange bearing, Thrust bearing and bright bar, all purchased from Technobots: - fast delivery! I just need to find a couple of crank handles - just in case I need to back off a motor or two in the future. I have two, but they have the wrong ID.

    The parts for the PSU should start arriving tomorrow. I will be following the plans set out within this thread:
    A Great thread.

    Having one motor to hand, will help with the setting out of the cabling.

    Started looking for a motion control cards - this seems to be a fair summary of all the basic points. I suspect it will be the last thing I buy - those 12 months will soon tick by:

    Dust extraction is mostly finished - up and over the table, as per the spindle cable.
    Last edited by Rich; 26-02-2015 at 02:46 PM.

  2. #32
    Rich's Avatar
    Lives in Warrington, United Kingdom. Last Activity: 08-04-2015 Has been a member for 5-6 years. Has a total post count of 30. Received thanks 1 times, giving thanks to others 0 times.
    Can someone let me know if it is normal to blow a fuse in the circumstances?

    I am in the middle of the PSU build, per the above thread, page 5. The basic circuit is complete, as shown in the following photographs. The initial test suggested the PSU was working - output 70vdc, so I start to solder a few of the parts together.

    Once the basic circuit was complete I tested how the circuit performed with the 24dvc regulated power supply - just arrived, running across the SSR. The test was simply switching it on and then off. At which point, I blew the primary fuse, tripped the primary switch and blew the 13amp fuse in the socket. The primary fuse was a 5 amp spade fuse - as no motors are connected

    I've not wired in the Relay 2 NC and I the eagle eyed will notice I've forgotten to wire in a secondary fuse.

    Is there an obvious reason for this? Or do I need to provide more detail.

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    Last edited by Rich; 07-04-2015 at 09:20 PM.

  3. #33
    I think it would be good if you put a schematic up exactly how you have wired it. Is that a RCD on the main fuse? If you have blown the 13A fuse you may have an earth fault. Is there a reason you are using an SCR in the circuit? What type of MCB have you used ie B type etc? ..Clive

  4. #34
    As Clive said, a diagram would be best. However I'll risk guessing - if you're connecting the transformer to the mains without a soft start socket, then the inrush current from charging the capacitors may be too high. Also, are those automotive type blade fuses and are they used on the mains or 70V circuit? If so you shouldn't use that type there as they're only rated for 12-24V. To be fair the fuse still seems to have worked... but that's maybe not the point!
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  5. #35
    I'm not an expert on electrics but I wouldn't use the automotive fuse on mains AC. Either MCB or DIN mounted glass fuse holder designed for AC would be my choice.

    I did a lot of looking into fuses for the DC side and concluded that it was ok to use a 5A 12V automotive blade fuse at 5A 70V because the fuse would blow at a certain power which is the current squared times the fuse resistance. The voltage didn't come into it until the fuse blew and the gap created needed to be big enough to prevent an arc ( therefore still allowing current through).

    That was where I got to it anyway. I also saw Irving use one ( with a disclaimer)!

    Clive - you wrote SCR did you mean SSR as in solid state relay?
    Last edited by routercnc; 08-04-2015 at 09:28 PM.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  6. #36
    Rich's Avatar
    Lives in Warrington, United Kingdom. Last Activity: 08-04-2015 Has been a member for 5-6 years. Has a total post count of 30. Received thanks 1 times, giving thanks to others 0 times.
    Thank you all, I can see I've made a mistake by using a spade as a primary fuse. The intention was to use a slow blow fuse, per the thread. I have one ... but because it wasn't on the purchase list, it dropped off the build list.

    I will draw a schematic and add a parts list, that will help clarify my issue and hopefully put me back on track.

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