Ratchet Mechanism on belt grinder

[Natlek]

So , for what purpose it is ? Easier to change belts or to hold steady tension on belts ?

 

[Tin.Man]

Tracks better as no shock to let the belt press into, plus it’s super nice to tighten it tight for roughing or loosen it for slack belt or cover grinding. Plus once your tooling arm is locked that’s all she wrote no more fiddling when you do change belts

 

[Geoff Flato]

Easier to change belts, great tracking, easily adjustable tension, its great.

 

[Kevin McGovern]

I thought about doing one when I designed my grinder. I kind of wished I had when I had access to free water jetting. I don't think it would be easy to accomplish without it.

 

[Natlek]

Easier to change belts, great tracking, easily adjustable tension, its great.

Geoff , can you explain little about tension ? No need for spring or gas tension spring ?

 

[Kevin McGovern]

Geoff , can you explain little about tension ? No need for spring or gas tension spring ?

correct. search for a video on the TW-90. you should get the idea.

 

[Natlek]

I thought about doing one when I designed my grinder. I kind of wished I had when I had access to free water jetting. I don't think it would be easy to accomplish without it.

On first picture /hand brake/ is ready to use/accommodate in tension arm , on second picture need little modification on teeth with fine file .Second one is from auto door window mechanism .........

 

[Natlek]

correct. search for a video on the TW-90. you should get the idea.

Thanks Kevin Now I know I did not have to follow the majority when I build belt grinder ...Thanks God , it is never to late to do right thing

 

[Natlek]

Well here it is .................ratchet mechanism for belt grinder made from handbrake of Mazda Millenia Big part is welded to head of bolt that hold tracking arm...so it remains in fixed position and because tracking arm is on two ball bearing I can tighten this bolt very tightly/First I tighten bolt then mark where to position that part , then took out ,weld and bolt all together .Plus thread is on plate which is 12mm thick and plus nut from back side to keep all in place . Small part is on tracking arm .The walk of tracking arm is more than enough for this small four wheel 2x42 grinder .Simple but works !
I like it ! Steady ,strong , teeth are small and they allowed fine tuning and I already see why it is better then spring. Need to weld small handle on that small part and to find spring It held all my weight when it is locked
On the first picture is the position where belt should all be tightened properly ...for fine tuning that position ,I will turn tracking wheel on proper dia. dimension last............

 

[john april]

the tw-90 ratchet will not wear out or get weaker like a kmg spring ( i own both) or change tension and be repeatable. when you push really hard into the platen, with a spring like the kmg, the belt will move to the side. pushing hard on the platen traps the belt with friction and the spring arm will actually move with the change of belt tension making the belt move to one side. i have not noticed this yet with the tw-90 but i have only been using it for a month so far.

 

[kuraki]

That looks good Natlek. The more teeth you have the better, the finer the adjustment the greater your ability to have variable tension. But you put your gear on upside down from the way I would have.

My first version is too coarse, too few teeth. It works fine, but there is a huge change in tension from one tooth to another.

 

[Natlek]

the tw-90 ratchet will not wear out or get weaker like a kmg spring ( i own both) or change tension and be repeatable. when you push really hard into the platen, with a spring like the kmg, the belt will move to the side. pushing hard on the platen traps the belt with friction and the spring arm will actually move with the change of belt tension making the belt move to one side. i have not noticed this yet with the tw-90 but i have only been using it for a month so far.

All that , and I think that belt starts to slip on drive wheel in that situation ....

 

[Natlek]

That looks good Natlek. The more teeth you have the better, the finer the adjustment the greater your ability to have variable tension. But you put your gear on upside down from the way I would have.

My first version is too coarse, too few teeth. It works fine, but there is a huge change in tension from one tooth to another.

I put my gear in only way it is possible to work .I just measured distance between hole on handbrake handle because that is most important mechanism to work correctly .Look in dimension on teeth , one side is wider where tooth from small part sit .Force from tracking arm act in this manner like I drew on picture ...I think ?
Now I have no place for ordinary spring ..where is blue square goes another 2cm thick part for tracking wheel so no place for spring . And that is good in some way .....So I will use flat spring , they last longer and there is no need to be very strong spring because as I explain pressure from arm push tooth in gear .........
What do you think ?

About your case , why you don't shorten gear ...I mind to be close to pivot of arm ? If it is closer , path will be shorter and with smaller tooth on gear will work better ? At least I think that in this moment .......I overheated my brain today from work on one motorcycle

 

[stezann]

It looks like a complicated build, it makes me wonder if a simple screw tensioning system would work.
To get repeatability one could tighten the screw by a dynamometric spanner.
One could say that with a screw system it might be difficult accomodating for the belts elongating/giving during use, but still i wonder how many times does the ratchet system actually jumps itself up a tooth in real use for the same reason?

 

[WC53]

Looking to try this for my current build, just need an easier way than a file to do the ratchet

 

[kuraki]

It would not be terribly difficult to grind them with good layout and a work rest.

 

[WC53]

I was just looking at the home depot 140 tooth osb blade for $5 and thinking hmmmm

 

[kuraki]

There's an idea. Cut it in 1/4s and double it up.

 

[P.Brewster]

So , for what purpose it is ? Easier to change belts or to hold steady tension on belts ?

The primary advantage is the ability to adjust tension when the belt is already installed (and/or when the machine is running).

 

[WC53]

I cut a cheap sawblade into 1/4s with the angle grinder, flattened the teeth with a hammer and stuck it together. Still working on the arm for the wheel and ratchet mechanism. El cheapo is getting closer to running. Got the vfd and belts in yesterday and nephew is back Sunday to resume work. He put some paint on it because he was excited....

Making a grinder with scrap would be much easier with a grinder.

Thanks for all the pointers