Archive for December, 2012

Bridgeport milling machine

December 23, 2012

To a mechanical engineer, a Bridgeport is the iconic machine tool, the basic necessity for doing precision work, and I’ve felt increasingly hamstrung by the inability to whip out simple components or modify parts we buy.  I looked at a smaller Jet machine, but it was missing a couple of degrees of freedom that I’ve actually found quite useful recently, it didn’t have quill feed or back gear, and I scraped my knuckles trying to adjust the five speed belt drive – I could have swapped the single phase motor for a three-phase and run a VFD, but that seemed like too much work for a compromised machine.  So I found a mid-eighties Bridgeport with variable speed on Craigslist, and checked it out last weekend.  It looked pretty good, so today Joshua and I went to southern NH to pick it up.

The owner was an older German gentleman who had made his living building big pieces of equipment, and he had a large forklift which made the loading part simple.  We had a half-ton pickup with a 1500lb flatbed trailer, and the pickup probably could have handled the whole tool (it has the heavy suspension b/c snowplow) but getting it from the high bed of the trailer to our shop floor would have been a real trick.  So we took the head assembly off the column and put it in the truck bed.  We unbolted the head assembly from the column and lifted it off with the forklift, then bolted it to a couple of 2X8s cross-wise, which we then screwed to a pallet and skidded it into the truck.  We then hooked up the trailer and arranged more 2x8s crosswise underneath the column, picked up the column, and slid it into the trailer, adjusting the position to get suitable tongue weight.  We used wide nylon ratchet straps left over from Joshua’s boat to lash it fore and aft, and got on the road.  I have had bad experiences hauling heavy loads in these little Snowbear trailers, so we took back roads for the first 20 miles or so, then stopped to check the tires (slightly warm) and wheel bearings (stone cold) before getting on the  freeway.  Fortunately we made it home without incident.  Here is how the load looked when we arrived:

the load

 

Then came the fun part.  Lacking a forklift, we had to resort to Egyptian methods.  We carefully backed the trailer until its rear end was over the threshold of the door, then chocked the wheels and jacked the tongue with a Hi-Lift jack until the tail grounded out on a 4×4 on the sill.  We then screwed some 4′ 2x scraps to the 4×4 to create a ramp, and rolled the mill onto the shop floor on 1.5″ pipe rollers, controlling the speed by snubbing against the hitch ball of the pickup:

jacking the trailer

 

rolling off the column

 

Once on the floor, we could roll the column around easily, though changing direction was more difficult.  The trickier part was getting the head assembly off the truck and onto the column.  We started by fabricating a u-bolt out of 1/2″ all-thread to hoist from, and installing it on the underside of one of the I-beams that make the (relatively unconventional but extremely stout) first floor framing of the south house.  We hooked a pulley to the u-bolt, and ran the bitter end of a rope-a-long through the pulley and to the eye on the top of the ram.  The main complication was that the truck was too wide to fit through the double doors.  So we fabricated a rudimentary platform to skid the head assembly off the tailgate and under the hoisting ring. We could have done a better job of this and the transition was a bit sketchy, but we had the assembly supported with the rope-a-long.  We also put a sling around the head itself and used a second pulley to keep it more or less level as we winched it up:

hoisting head assembly

 

From there it was relatively simple to lower the head assembly onto the column and bolt it together – there’s a funky spider casting that holds the head down, but with a bit of fiddling we got it lined up.  We skidded the assembled mill (significantly more top-heavy now) into its assigned corner, and set it down on some rubber pads:

in place

 

Next steps include leveling the machine, wiring it to the VFD I bought, tramming the head, and throwing up a fast-and-nasty partition to keep the wood dust from the rest of the shop out of the works.

Fruit calendar early 2013

December 2, 2012

Fedco dates: (http://fedcoseeds.com/trees.htm)

Discount deadline: January 18th (final March 8)

Scionwood deadline: Feb 22nd (ships March 20)

Preorder tree sale: April 26/27

MOFGA scion exchange: March 24 (also a grafting lesson IIRC)

MOFGA grafting workshop: April 28 (I hope this is updated; it doesn’t say 2013 anywhere on the page)