Drive sprocket size for milling

[Green Man Home and Garden]

I am new to the world of milling and need to rip some 3 ft oak trunks in half to get them to a manageable size to get them out of a wet location and transport them for milling on a rack saw.

I am looking to mate a ms880 with a 36" Duromatic E bar running a 3/8" 10deg ripping chain all mounted on a Granberg mini mill.

I need to replace the .404 rim sprocket for a 3/8" sprocket and would like any advice on using a 7,8 or 9 tooth sprocket or indeed any disadvantages of my proposed set up.

Many thanks.

[Stubby]

My thoughts would be that if you are cutting the full length of the bar and in oak then use a 7 and rely on the torque . Just me .

[Green Man Home and Garden]

Thanks, does the rest of the set up sound OK.

[doobin]

880 should be great on a 36in bar.

 

I'd get all three sprockets and a chain to fit the largest. Hopefully it flies on an 8 or 9, if not then all you need to do is remove a link or two.

 

If one chain length fits all (unlikely but you never know, it should be OK on two of the sprockets though) then you're laughing, and can pick the best sprocket according to what you're milling at the time.

[Rob D]

I'd try and stay clear of the duromatic bars if possible - nose gets hot and causes problems but fine in the short term.

 

 

Personally with an 880 I'd stick to .404 chain - better chip clearance and stay sharp - 3/8 saves negligible kerf and is no faster (In my experience that is - some like it!).

 

 

Run on a 7 pin - torque is what you want not chain speed even with an 880 it has to work hard.

 

 

If in doubt play around with options as everyone has their favourite and ideas of what works best - I know someone who runs .325 chain with x2 MS880s on a double ended set up... they like it and have had no problems although not something I would do.

 

 

[Green Man Home and Garden]

Thanks for your help.

My 880 came secondhand with the duromatic E bar and two new 3/8" ripping chains so I was hoping that set up would get me going. I've only been able to source an 8 tooth 3/8" rim sprocket through enquiries this morning so I am going to have to try that and see what it's like. It's coming from FR Jones, can you recommend another online supplier ? Failing that I'll have to get my local dealer to order a 7 tooth in.

[Stubby]

Shed loads on fleabay .......

[C.J]

I take it your clutch drum is a standard 7 spline .

 

I find it hard to believe FRJ cannot find you a 7x3/8 rim.

 

I'm sure Rob D can supply you an Oregon 68210

 

Your choice of 7 or 8 pin may depend on which fits the number of links on the chain .

 

9x3/8 is for racing saws and will be hard to find.

[agg221]

If you are going to have to buy something anyway, I would buy a chain rather than a sprocket. 3/8" chain is going to be restrictive in the long run, as getting a sprocket-nosed large mount bar will be difficult.

 

36" bar on a mini-mill works OK (I use one) but it may not run dead straight. I sometimes get a little bit of wander in the nose end, and I'm using an 066 which is a bit more manageable, so be ready to true up the face on the racksaw. Also, bear in mind that a 36" bar will give you about 80cm of actual cutting depth on the mini-mill, so you will either need to complete the other 20cm of the cut. You could cut, roll a quarter, cut, roll a quarter, cut, then roll up the cut to horizontal and freehand from the other side or finish with steel wedges (if doing this, still roll it up and split from the end and inwards from the outside, rather than be tempted to just widen the saw cut, as this will just make it split randomly - always split from the outside inwards).

 

Alec