Drilling multiple holes in a line.

[Reb954]

I would still suggest drilling a 1/4" pilot hole thru the peg board after center punching each location, then open it to 3/8". That is a lot of holes so the 1/4" bit will drill thru easier than a 3/8" bit. If the OP has a good split point cobalt drill bit then he could go with that instead of using the 1/4" first, but most people just have hardware store bits.

Example: a 1/4" hole is .0491 sq. in. of area to drill. A 3/8" hole has .1104 sq. in. of area which is 2.25 times more than the 1/4" hole.

Also, assuming he uses the peg board, the 1/4" bit will line up in the holes where the 3/8" bit won't.

Edited for clarity.

 

[CalG]

You know, a 3/8ths diameter hole saw is just plane foolishness. Only thing I can figure is that some folks choose not to read the original post.

A note to the original poster. If you select angle iron for your beam, and choose to drill from the inside of the legs. You will need to center punch the starting locations. The little bit of slope that is typical of structural angle steel is just enough to keep the drill point walking. Hot rolled always has it's warts and pimples that can push a sharp point around.

A 3/8ths drill bit will wander less than smaller "pilot drills" when both are fitted to your drill press,
because it is stiffer.

 

[/pine]

IMO...the KISS method to do this with a drill press is to clamp and secure an extended fence and table to the drill press...

The fence will set the offset dimension so no layout is mark is required...secure a tape measure to the table extension the length of the rake tine stringer...just slide the stringer 2" for each hole from one end or the other...this eliminates any need for the 2" spacing marks...

so there is no need to layout any/all the hole marks...use a centering bit and there is no need to center punch...no need for any templates or jigs...the fence and the tape measure are the jig...

If the fence is secure and the stock is moved exactly 2" each time it will be as accurate as using any layout etc...this is not a piano...

 

[jmc]

Going to a lot of extra trouble to hold the drill hole locations within a gnat's bottom may be a waste of time if the spring tines are all over the map- off center holes, off axis holes, forming tolerances, heat treat distortion...

 

[Reb954]

I finally had a chance to take some pictures of a rake bolster I made quite a few years ago, maybe some of the ideas I used may help the OP. This rake was only made for an ATV so it is 60" long and lighter duty than would be needed for a tractor.


Initially I had a company bend the plate into a channel shape. I have a mill so drilling the holes and machining the slots was easy but took a lot of time. Once I had built mine, several people said they wanted one after they saw how effective and versatile it was so I did the layout work for the bolster as well as some other parts to be made using a laser cutter. Then I just contracted out those parts which saved me a lot of work and saved the customers money.

Following is the bolster which was laser cut out of a sheet of plate, then bent as needed. Basically I just adapted the York rake design to an ATV and bought the tines from them. A single bolt holds the tine in and the slot keeps the tine straight.


Following is the complete system with the box blade, S-tines and rake on it. Two pins hold on which ever implement I need which includes the box blade, rake, back blade and a bank of S-tines. I also have a scarifier that works in conjunction with the rake and box blade.

 

[HCJtractor]

That’s really nice. I wish I had the ability to cut 50 square holes but I can’t do that. Plus I need a stronger frame than the 1/4 “ plate. But that looks very well designed and made.

 

[Egon]

Cut slots in angle iron and bolt it on. Give the same results. Quick work with an angle grinder.