Retrofitting a 1986 Maho MH400E

Can the centroid or MACH 3 close the position loop with the Heidenhain scales, or are you just closing the loop between the motors and the gecko's, and leaving the controller to drive open loop?

As a comparison my retrofit cost about:
$100 - Old PC
$400 - MESA 5i25/7i77 plug and go kit plus 7i84
$20 -a couple of patch cables.
$140 - 2x 602 EXE's to fix existing failed components.
$100 - misc wire, ferrules, buttons, etc

So for under $800, I have the gearbox control, the µm accuracy Heindenhain scales in the loop, the hydraulic pump, and coolant pump under machine control. If you hadn't ripped everything out, you'd have $800 to pay for a repair or replacement of the transformer.

I have paid more than that because I made the custom control module, but that is optional.

The hot face is one of the Comprit products by RHI. This is an industrial refractory product rated for 1650°C (3000°F) processes. Apart from a couple of cracks and slag spatters, the heat does nothing except ensure a high Mullite content, and therefore great strength at temperature. My first furnace had a mullite hot face made to a recipe on Alloy avenue. But I cut corners on the lid and used hardware store chimney grout. It turned to lava and dripped during the first firing. Myfordboy has an excellent how to video series on making a furnace with a cast refractory hotface and Kaowool insullation. I'd recommend copying that design. Mine is similar, but takes advantage of scrap Calcium silicate insulation I already had.
Mark

Mark,

I'm not too concerned about the linear encoders or the gearbox. On a machine this old and having no way to properly test anything, I'd rather just stick with what I know...at least on the first machine. My experience with older CNC machines is that it's only a matter of time before something gives up, and that part is usually expensive. I'll be using this machine for my business and it won't be making parts that need really tight tolerances. Speed control will be a breeze using the VFD. If I really need a low gear or high gear, I can change the gears manually. I don't see that being needed very often.

It seems the hydraulic unit is tagged as 380v but works fine with the 220v 3 phase, no issue releasing tools. Controlling the solenoids with a relay block is straight forward. I know there are benefits to the linear scales and the gearbox, but they aren't important for my application. It's more important for me to be able to have a capable machine that is cheap to repair and easy to troubleshoot. If I have an issue with any of these parts I'll be able to diagnose in a couple minutes and have a new part within a couple days.

Not knocking your route, I may try it on the next machine.



Bob,

I don't stock any of the foundry herbs. It is more of a hobby project than anything else. It's a diesel fired furnace and yes, I was using fire brick. Sounds like I need to upgrade. Most pouring I've done has been Si bronze and aluminum.

I'll be running the machine off of three phase 220v. Speed will be controlled by a 0-10v signal sent from the controller to the VFD. I'll find a happy medium gear and use that as the baseline.

Also....it's getting cold.

eflor8234
Happy -almost New Year --
Can get by using fire brick for most of the non ferrous metals an pottery but at temperatures needed for iron the result can be a crucible glued to the furnace bottom . Noodle about the Keith Rucker videos as I remember he said the name of refractory he is using.
Kaowool is available this side of the Atlantic as are the cast able refectories. What size crucibles are you using?

Interesting the hydraulic pump running on 220 volt , could be interesting to know what the motor current draw is per phase.
Guess my question about your 3 phase power should have been - do you have 3 phase power or are you using a phase converter to derive it? Ohio doesn't trust home owners to have 3 phase power.:laugh:
What are you going to do with the transformer you removed ,as I might be interested in it?
Could you get a photo of the Exe Board (converts the heidenhain scale 11micro amp signal to 5? volt level) . Am interested in the components side of that board.

Bob

Bob,

Happy New Year.

You're right about the fire brick. I used it without issue melting aluminum and bronze. Higher temps quickly glazed it. My daughter enjoyed collecting the "blue jewels" when I chipped away some of the melted brick. At some point I'd like to rebuild the furnace and will look into some of the higher temp options you guys have mentioned. I'm not sure which size crucible I have. A friend of mine has a small production foundry near me. He gave it to me the last time I visited his place. I'm not at my shop but I'd guess it's about 14" tall and 8" wide at the top. It's heavy when full of bronze.

I had to build a rotary phase converter for my shop. Local power company wanted $12k to run a three phase line under the road to my shop. I'll know I've made it big when I can pay them to bring it over.

All the transformers from this machine have gone the way of the scrap yard but I have another 600E that hasn't been touched. It has the large transformer that is separate from the machine and then the other three or four that are in the box. I can load a pallet if you're interested. Are you near a Fastenal location?

Here are some pictures of the EXE board and the machine as it currently sits.

Question about the scales and EXE board. Can these be run to a DRO like you'd find on a typical manual machine? I have a couple manual machines that would benefit from a set of scales.

Erik

Erik
That crucible is large ,as I tend to think of how many quarts of usable melted metal there will be. Yes I think it would be heavy and lots of heat , way more than I could handle. To me backyard metal casting involves three separate disciplines. One is pattern making which 3-D printing an Cad-Cam have made a huge difference in. Two is mold making , witch oil bonding sands and moisture meters for regular sand molding have helped. Three is the melting part where induction heaters are available for less than pint quantities of metal an affordable temperature meters have become available and also some of the newer high temperature insulating materials.
.Your Exe board looks like one I have . My thinking is it seemed to be a transition phase to the micro components boards Yes ,some of the older Heidenhain displays could use those scales an Exe Bd. Think the DRO display of your MH400P might be able to use them. The LS403 scales output a 11Micro Amp signal and the Exe Board converts that to a 5volt TTL square wave signal . So the question is, will the DRO read a 5 volt TTL square signal ?

I am about three blocks from a Fastenal store ( or was ,but in today's economy would have to recheck ) an last time I was there they had replaced all the personnel for the second time last year.
The large transformer that is separate may be the 208 thru 528 volt to 380 volt three phase Xfmr. that was included with every machine sold in the U.S.A. Yes I would be interested in the transformers .
But :
Think you might consider hanging on to them until after your first conversion convinces you that Linux CNC is not something to try.
Also I would rather drive up to Northern Michigan this coming spring after the snow , ice ,salt an brine , than pick up a pallet at Fastenal. Do realize your shop has limited space and is not a warehouse .

Bob

Bob,

Foundry work is a fascinating field and I would agree with your three part outlook. After making some patterns, I now understand why there were many tools referred to as pattern making tools and vises. It is tedious work. I have made a handful of patterns using CNC equipment...much faster and draft can be programmed into the CAD file. Thanks to the guy that gave me the crucible, I have a lot of five gallon buckets filled with petrobond oil sand. He needs to capture very fine detail in his work and rotates sand out that would still work fine for amateurs like me. Saved him the hazmat fee of getting rid of the stuff.

We can touch base in the spring about the transformers. I honestly don't know much about Linux CNC. I know it's there and that a lot of people use it with good results...that's where my knowledge ends. I joined this forum specifically for the Maho thread since it seemed to be the only active discussion about the older machines. I look at it like I look at going out to eat- once I order something I like, I'll always order that same thing off the menu. I know there are other things I'd probably like but, for better or worse, I stick with what I know.

We can touch base in the spring. I'm guessing the components will still be floating around the shop.

Erik