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All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Wood Chop Shop (Working with wood) => Topic started by: Ronno6 on November 28, 2020, 10:26:01 PM

Title: Crosman 2100/2200 Forearm
Post by: Ronno6 on November 28, 2020, 10:26:01 PM
I have several Crosman 622 Buttstocks that can be made to match up well to 2100/2200 receivers.
But, I am at a bit of a loss trying to figure out how to make the forearm/pump handles to match.

Anyone care to pass along any pointers?
Title: Re: Crosman 2100/2200 Forearm
Post by: Ronno6 on April 06, 2021, 10:11:31 AM
The large round bottom trough in the forearm wood blank was no problem.
It is that pesky flat then rising profile groove for the metal pump arm lever which has puzzled me.
 
After many hours of musing over how to rout that varying depth groove in the bottom of the forearms,
I have hit upon a process.
I have several routers, one of which is a Hitachi M12V plunge router.
My plunge router is spring loaded to raise the cutting depth when not held down.
And, the motor section has 2 large handles which are round at the point where they attach to the motor.
So, a profile cam riding atop the handles will plunge the depth to the desired dimension, then allow the motor to rise as designed
at the appropriate point and to the correct profile desired by riding along the underside of the cams.
I am awaiting the template guides, bit collet and ball nose end mill to get this show on the road.........

I suppose this could all have been done by hand, but I desire a process thru which I can get accurate, repeatable results.

Next it will be on to fixturing so I can drill the spring pin attachment holes.
Title: Re: Crosman 2100/2200 Forearm
Post by: Blowpipe Sam on April 06, 2021, 12:01:16 PM
Iím planning to make a wood stock for my 2100 and I have been pondering how to do it.  My plan is to make a laminated stock out of thin panels glued together.  I intend to make the forearm out of five pieces.  The inner three pieces will be cut to shape to fit the pump tube diameter and the central piece with the ďtrenchĒ will be shaped by tracing the pump arm lever on the side of the  panel and then cutting it out before gluing the whole thing up.  Final fitting can be done by wrapping the pump tube in sandpaper and using it to smooth the interior of the forearm for the final fit.
Does that make sense? :o
Title: Re: Crosman 2100/2200 Forearm
Post by: Ronno6 on April 06, 2021, 07:16:18 PM
That oughta work.
Can't wait for pics on that one!

Routing the groove will allow me to use a ball end mill, as the profile of the pump lever has round bottom.

I like elegant....and repeatable....
Title: Re: Crosman 2100/2200 Forearm
Post by: Blowpipe Sam on April 06, 2021, 10:55:44 PM
I own several routers.  I inherited all of them.  I have no idea how to use them and never have. My plans are based on what I think I can accomplish given my primitive carpentry skills.  Weirdly, I know something about gluing up laminates, so that is the direction Iím taking.  I wish I had your skills with power tools!
Title: Re: Crosman 2100/2200 Forearm
Post by: Ronno6 on April 06, 2021, 11:16:56 PM
I own several routers.  I inherited all of them.  I have no idea how to use them and never have. My plans are based on what I think I can accomplish given my primitive carpentry skills.  Weirdly, I know something about gluing up laminates, so that is the direction Iím taking.  I wish I had your skills with power tools!

My father was a cabinet maker. I picked up much thru osmosis...
i was a mechanical buyer for 30 years and learned much about fixturing and machining.
I have many wood buttstocks which I adapt to fit the Crosman pumpers and I need to produce quite a few forearm/pump handles.
'Twould be a different story if I was just doing 1 or 2......

On a side note, I camped at a campground in Panacea on the banks of the Sopchoppy while on a bicycle trip about 10 years back.....FWIW
Title: Re: Crosman 2100/2200 Forearm
Post by: Ronno6 on April 11, 2021, 11:00:41 AM
The cam plate idea was a good one....sorta.
I opted for putting the cams under the router handles rather than above.
I found that pushing the router down and having the cams force it up was more reliable than
trusting the router's spring to force it back up from plunge depth.
So far, the slot depth profile is perfect, but I need to elevate it at the front end to orient the slot.

I had been attempting to work with 1-1/2" square wood, but that is not gonna be suitable, as the depth of the bottom
groove does not leave much thickness for strength.
I have located a seemingly reasonable source for 1 3/4" square hardwoods, and have some various species on order.
This is going to make a slight retooling necessary to deal with the ​larger thickness.

I also need to pay closer attention to the direction of the grain............

Here are a few  (horrible) photos of the  fixtures:

Title: Re: Crosman 2100/2200 Forearm
Post by: Ronno6 on April 13, 2021, 10:15:11 AM
I purchased some 1-3/4" square dowels from HD yesterday. S'posed to be hardwood, but don't think so.
They are actually laminated form 2 pieces of wood.
Gonna use them as test subjects for the process before possibly messing up the expensive stuff.
First, rout out the 3/4" wide  round bottom  deep slot.
Then rout the pump lever groove.
I have to make a fixture to drill the cross-pin holes.
Next will be the shaping of the front end to match the Crosman "clam shell's" curvature.
After that, the shaping and sanding will commence, followed by staining and finishing.

Fingers crossed...........
Title: Re: Crosman 2100/2200 Forearm
Post by: Ronno6 on April 16, 2021, 05:10:59 PM
Well........................
Here is attempt #1.
Often my first attempts are the best (not so in matrimony.....)

This forearm is made using what Home Depot calls "hardwood."
Not really too hard; looks like pine, but not really sure.
I amusing this as it was way less expensive stuff (Oak, Maple and Cherry) which I have on the way.
Finish really isn't great, but that's not important right now. Stain has been applied but no finish.
Shaping of the wood is pretty labor intensive, but I shaped it more like the Crosman wood forearms than the more boxy style of another custom stock/forearm which I acquired as part of a Crosman 2200 deal so I could check it out....

Photo 5 shows a prior attempt and compares 1t to a Crosman Model 1 forearm.
Please pardon the clutter............