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crowie
475 posts
and
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in over 1 year
Could I please trouble you for some assistance thank you.
Could I please trouble you for some assistance thank you.
I’m in the process of building an excavator at the request of one of the grandsons.
It’s a bit of a mongrel as I’m using two sets of plans; one for the body and the for the digger arms plus lots of fudging and guess work.
I’m up to making the hydraulic rams using 8mm dowel for the rods & 19mm dowel for the cylinder; both Tassie Oak (Aussie Hardwood).
As I don’t have a lathe, I’ll use an engineers vee block and a bradpoint bit on the 19mm in my drillpress.
My question is by just drill an 8mm hole with the bradpoint bit into the 19mm dowel, is that sufficient enough to make the ram functional?
Extra information.
The actual plan suggests a 1/4” steel rod going into a 1/4” x 3/8” nylon tube inside the 3/4” dowel.
The plan is in imperial measurement which I’ve been working through, but saying that it’s sparse on details.
I’m in the process of building an excavator at the request of one of the grandsons.
It’s a bit of a mongrel as I’m using two sets of plans; one for the body and the for the digger arms plus lots of fudging and guess work.
I’m up to making the hydraulic rams using 8mm dowel for the rods & 19mm dowel for the cylinder; both Tassie Oak (Aussie Hardwood).
As I don’t have a lathe, I’ll use an engineers vee block and a bradpoint bit on the 19mm in my drillpress.
My question is by just drill an 8mm hole with the bradpoint bit into the 19mm dowel, is that sufficient enough to make the ram functional?
Extra information.
The actual plan suggests a 1/4” steel rod going into a 1/4” x 3/8” nylon tube inside the 3/4” dowel.
The plan is in imperial measurement which I’ve been working through, but saying that it’s sparse on details.
Cheers Peter
Life’s Good, Enjoy Each New Day’s Blessings
12 Comments
Hi Peter,
I am not a model builder, but it seems that the wood-to-wood connection would bind up with the seasonal changes. It sounds like the plan details would work better. You would have the strength of the steel rod and it should slide in the bushing; I would also think that there should be a collar around the end of the arm to strengthen the connection there. Best of luck and looking forward to seeing the final project.
I am not a model builder, but it seems that the wood-to-wood connection would bind up with the seasonal changes. It sounds like the plan details would work better. You would have the strength of the steel rod and it should slide in the bushing; I would also think that there should be a collar around the end of the arm to strengthen the connection there. Best of luck and looking forward to seeing the final project.
Main Street to the Mountains
I'm curious about the lenght?
My dad made several models over the years. His hydraulic cylinders were always wood. They have worked out fine. I'm pretty sure it is all about having enough clearance to prevent any binding. No caps on any of them.
I think it could be functional either way. As Steve said, I’m sure a wooden rod would work as long as the clearance isn’t too tight. A wax finish on the rod would help too.
If the model is meant too look somewhat realistic, I’d lean toward an aluminum rod. When I see heavy machinery, I always notice the polished metal hydraulic rods.
If the model is meant too look somewhat realistic, I’d lean toward an aluminum rod. When I see heavy machinery, I always notice the polished metal hydraulic rods.
Welcome to Craftisian, Peter! Tassie Oak should be hard enough to function, but as Ron says, aluminium may look better. If the rod ends up being too loose, a wrap with string on the end inside the ram may seal it up enough to give it a proper-feeling amount of drag. I’d say give it a try and tinker a bit.
May you have the day you deserve!
Thank you gents for the constructive assistance.
I’m going to have a go at making one of the four rams todays using the timber.
I’ve recently bought some Bubblechute Shop Wax so will polish the piston rod with that for smooth operation in the cylinder.
All the cylinders are 4.5” (115mm) to 5.5” (140mm) in length.
I’m going to have a go at making one of the four rams todays using the timber.
I’ve recently bought some Bubblechute Shop Wax so will polish the piston rod with that for smooth operation in the cylinder.
All the cylinders are 4.5” (115mm) to 5.5” (140mm) in length.
Life’s Good, Enjoy Each New Day’s Blessings
You could possibly find a 3-5 mm dowel and wrap some sand paper around it and lightly sand the inside of the whole out to slightly enlarge it if it's too tight until you get the right amount of friction.
I would made the hole about 8,5 mm. Normally I first drill a 8 mm hole with a bradpoint drillbit. After this is done I use a 8.5 mm metal drillbit.
However, I often have problems with making the hole parallel. I would use square wood from about 20x20 mm, drill a hole from 8 mm and put a 8 mm dowel in it (tight fit) When you need 115 lenght I would made the lenght 125 and use a drip superglue at the ends. This dowel should stick out on both sides. One side of the dowel than is placed in the drillpress chuck and the other side I would place in a ball bearing. Then I would turn it to 18 mm round with using a chisel and a chisle support. Doing it this way your hole is 100% centric.
For a toy I would consider a 10 mm piston.
If my english explanation falls short, you can always contact me, but for now I'm going to bed.
Start at approx 6 minutes;
However, I often have problems with making the hole parallel. I would use square wood from about 20x20 mm, drill a hole from 8 mm and put a 8 mm dowel in it (tight fit) When you need 115 lenght I would made the lenght 125 and use a drip superglue at the ends. This dowel should stick out on both sides. One side of the dowel than is placed in the drillpress chuck and the other side I would place in a ball bearing. Then I would turn it to 18 mm round with using a chisel and a chisle support. Doing it this way your hole is 100% centric.
For a toy I would consider a 10 mm piston.
If my english explanation falls short, you can always contact me, but for now I'm going to bed.
Start at approx 6 minutes;
Maybe this is that excuse to get a lathe crowie.... yeah, yeah... space... only between the ears... I'm sure you have a tool that can be piggy-backed on a flip stand (good excuse for a next me-me project)... another tool with the same footprint.
Life without a lathe is like getting on a boat/ship without a floatie.
Life without a lathe is like getting on a boat/ship without a floatie.
If your first cut is too short... Take the second cut from the longer end... LBD
Sorry Ducky, but there is absolutely no space for a lathe. I’d need to excavate another 16tonne of sandstone out from under the house plus redo all the piers & bares!
Life’s Good, Enjoy Each New Day’s Blessings
Sorry Ducky, but there is absolutely no space for a lathe
Peter please make a picture from your drillpress when you are turning the parts. Then rotate that picture 90 degree, post it here and let LBD know that you have bougth a lathe. He will never see that you have rotated that picture :)
Sorry Ducky, but there is absolutely no space for a lathe. I’d need to excavate another 16tonne of sandstone out from under the house plus redo all the piers & bares!
So!!! What's the problem? That 16 isn't as bad under metric...
Then rotate that picture 90 degree,
Will not work... all these new sites correct photo rotation.
If your first cut is too short... Take the second cut from the longer end... LBD
