On May 22, 2020, at 6:24 PM, Ryan K <grizzlybagworks@gmail.com> wrote:
It took me almost 2 years to finish but I think I'm pretty much done with the 5914 teardown/rebuild. Overall I really love the machine but the Reeves drive+timing belt drive, even when properly rebuilt, was simply too loud for my liking. Shame because I spent a lot of time/money rebuilding the countershaft and the rest of the components.
What I ended up going with is a direct drive system using an 8 rib poly-v belt. I chose a 2hp Marathon Black Max Inverter Duty/TENV motor paired with a Hitachi WJ200 VFD+47ohm 500w braking resistor. Speeds are same as stock with a 1:1.75 pulley ratio. Machine runs 20hz to 120hz. Machine stops faster than the stock clutch/brake and starts faster as well. I have dynamic braking setup but haven't set up DC injection braking yet.
My main concern was that 2hp wasn't going to be enough power going direct drive. At 20hz you're looking at .66hp at the spindle. DOC and Feedrate are linearly proportional to HP so the idea of drop my DOC by 1/3 didn't thrill me.
I decided to chuck up some material and run some tests. The results have put my concern to rest. Being able to move between carbide and HSS tooling I'll be able to stay in the machines "powerband". But even on the outskirts of that power band the performance is more than acceptable for me. At 20hz in 1.25" 4140 I'm able to peel a .150" DOC (.300" diameter) at .015" feed rate. A cutting force calculator would tell you that you need ~2hp spindle to do this, hence original my concern. (https://www.kennametal.com/us/en/resources/engineering-calculators/turning-calculators/cutting-forces.html).
Here's a video of the machine in action performing Clausing's "Chatter Test". This is actually a more strenuous test that the original as I'm taking an additional .025" DOC and the material is 1/4" smaller in diameter. At 1.25" diameter the stick out should have been around 4.16".
I just thought I'd share for those of you that may be struggling with the Reeves drive and want to do something simpler, smoother and quieter. I'm willing to trade off less power for that 5% of the time I may need it for a dramatically quieter and smoother machine for the other 95%.
Here's the specs on the cut:
.150" Depth of Cut (.300" Diameter) (Original Test Called for .125")
.0026"/rev feed rate 360 Rpm (HSS) 1.25" hot rolled 4140 (annealed) (Original Test Called for 1.5") 5" stick out, Unsupported
https://youtu.be/EFmI_R3GHSU
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