2 X 72 Grinder Question

B

Broken Forge

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Jan 21, 2016
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I am building my own 2 x 72 grinder. I already picked up a 1 hp 1800 rpm single phase motor and bought the wheel set from Oregon Blade Maker. What I am wondering about is if that single speed is going to work or if I should invest another $100 in step pulleys to get some variation in my speed control? Ideally I would like to be able to use the grinder up to 220 grit and not just for rough material removal. Are variable speeds a necessity or can I get by with the one speed for a while and upgrade later?
 
Most definitely spend the extra to get at least a 3 step pulley system, it's worth the little extra cost. :thumbup: Get 3 feet of the "Powertwist link" belt for your drive belt, that way you can customize the length you need for it to fit tightly around the pulleys. You can buy the Powertwist belt here, just make sure you order a quantity of "3", because it sells in foot long pieces. http://usaknifemaker.com/knife-maki...99/power-twist-link-belt-by-fenner-drive.html

I have a 3 step pulley system ( 2", 3" & 4") on my grinder as well as a 1hp motor with pretty much the same RPM (1745) and I'm using a 4" diameter drive wheel. If you're also using a 4" drive wheel then you'll have about the same speed as my grinder. I'm mentioning this because below I'll post a video of my grinder which shows it running at it's slowest speed (which very is nice for more controlled grind work, such as dialing in the plunges, finish grinding etc.) , this way you can get an idea of about how "fast" the slowest speed is. Also, it goes plenty fast on it's highest speed, which I rarely use since the middle speed is fast enough for me most of the time.

[video=youtube;aNMuKGMcqlc]https://www.youtube.com/watch?v=aNMuKGMcqlc[/video]

Hope that helps. :)

~Paul
My YT Channel Lsubslimed
... (It's been quite a while since I've posted any new vids)
 
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Yes get the step pullys, you need some way to adjust the speed.
 
To not open a new topic I'll ask here . I'm almost done with my 2x72 grinder made from scrap steel . These days I will make wheels . My question is what belt speed you will selected / surface feet per minute / If must be only one ? I need only one speed , just for rough material removal ?

11cabg1.jpg
 
Thanks David , but I would not spend any more money than needed. Frankly, I do not know why I engage in this project . I m not knifemaker and i make here and there some knives for me , family and some close friend . I have already 3 ph . motor 2800 rpm . which will run on belt/pulleys . One speed will be sufficient ...... for now . After all I read here I m thinking on something around 25m/s ? I can make 3 step pulley system eventually , but again , which 3 SFPM ? I have no expirience at all with belt grinder .....
 
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Broken Forge said:
I am building my own 2 x 72 grinder. I already picked up a 1 hp 1800 rpm single phase motor and bought the wheel set from Oregon Blade Maker. What I am wondering about is if that single speed is going to work or if I should invest another $100 in step pulleys to get some variation in my speed control? Ideally I would like to be able to use the grinder up to 220 grit and not just for rough material removal. Are variable speeds a necessity or can I get by with the one speed for a while and upgrade later?
Click to expand...

YES! "Generally", There is that word again:rolleyes: The finer the belt grit the slower you want to run. All belts have a sweep spot in speed depending on the grit and how you grind wood, steel etc.. Only cry once! Get the step pulleys.

You will be able to get close to that sweet spot and then start putting aside say $20.00 from every knife you sell till you have a coffee can with enough to get a VFD Variable speed control.:thumbup:
 
Yes, I second what Laurence said about speed and grinding. If you can get the pulleys and jackshaft cheap then do that but if there is any way you could afford to buy a VFD then do it. Once you control the speed of your grinder your work will improve greatly in my opinion. Step pulleys can work well too but nothing beats variable speed drives. Larry
 
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