[Sperstad]

Hello people.
Anyone know where I can find parts to my IH mill, so that I can drill 20mm (4/5 inch) holes? Need to find a big chuck and some big drill bits, if that is the best option for drilling 4/5" holes?

Hoping that someone can help me!

[SCzEngrgGroup]

Hello people.
Anyone know where I can find parts to my IH mill, so that I can drill 20mm (4/5 inch) holes? Need to find a big chuck and some big drill bits, if that is the best option for drilling 4/5" holes?

Hoping that someone can help me!

Any decent tool supply vendor should have drills with reduced shanks - Get a 20mm drill with a shank that will fit in an existing drill chuck or collet. If you need an accurate hole, a boring head will do a MUCH better job.

Regards,
Ray L.

[philbur]

The simplest is what is known in the UK as a Blacksmiths drill bit. They are large diameter drill bits that have a shank with reduced diameter. Unfortunately I don't know the Norwegian name.

Have a look here for an example.

http://www.toolfastdirect.co.uk/acat...hs_Drills.html

I think you will have to drill in steps to avoid slippage.

Phil

Hello people.
Anyone know where I can find parts to my IH mill, so that I can drill 20mm (4/5 inch) holes? Need to find a big chuck and some big drill bits, if that is the best option for drilling 4/5" holes?

Hoping that someone can help me!

[philbur]

Here ya go:

http://www.luna.no/webspeed/katalog/...=4&katsektnr=7

Good old Luna. Not cheap though, but that's Norway.

Phil

Hello people.
Anyone know where I can find parts to my IH mill, so that I can drill 20mm (4/5 inch) holes? Need to find a big chuck and some big drill bits, if that is the best option for drilling 4/5" holes?

Hoping that someone can help me!

[philbur]

If you want cheap mail order from here:

http://www.chronos.ltd.uk/cgi-local/...mith&TB=A&GB=A

[Andre' B]

In the US those are known as Silver & Deming drills.
http://www.owwm.com/mfgindex/detail.aspx?id=1017

Seems like one of those items that is just so oblivious that would have been "invented" many times by many people.

[Sperstad]

Thanks allot guys!

These Blacksmiths and Silver & Deming drill bits looks like a very good option. But i probably have to drill atleast one hole first. So that will be a bit time consuming when a shall drilll many holes. But I quess I can`t drill the hole with a boring head directly? (the plate is 5mm thick).

Another option is to buy a R8 end mill holder, and a end mill that can bore horistonal. But this is kind of expensive beacuse I have to buy a R8 holder for each end mill dimension.

So what do you think guys? With option do you think are the best?

Luna is not an option, way to expensive

[SCzEngrgGroup]

Thanks allot guys!

These Blacksmiths and Silver & Deming drill bits looks like a very good option. But i probably have to drill atleast one hole first. So that will be a bit time consuming when a shall drilll many holes. But I quess I can`t drill the hole with a boring head directly? (the plate is 5mm thick).

Another option is to buy a R8 end mill holder, and a end mill that can bore horistonal. But this is kind of expensive beacuse I have to buy a R8 holder for each end mill dimension.

So what do you think guys? With option do you think are the best?

Luna is not an option, way to expensive

Unless you have CNC, a drill will be the fastest way to make a large hole, even though you'll have to drill more than one size to get there. You could do it with an endmill and a rotary table, but that won't be any faster on a small machine. If your spindle motor can handle it, drill the first hole about 1/16" undersize, then re-drill to the final size.

Regards,
Ray L.

Regards,
Ray L.

[EvanVH]

Thanks allot guys!

These Blacksmiths and Silver & Deming drill bits looks like a very good option. But i probably have to drill atleast one hole first. So that will be a bit time consuming when a shall drilll many holes. But I quess I can`t drill the hole with a boring head directly? (the plate is 5mm thick).

Another option is to buy a R8 end mill holder, and a end mill that can bore horistonal. But this is kind of expensive beacuse I have to buy a R8 holder for each end mill dimension.

So what do you think guys? With option do you think are the best?

Luna is not an option, way to expensive

What about a shell mill (?). They leave some of the material in the center of the hole. Kinda like a hole saw but it will drill through thick material. They are not cheap but will drill a big hole start to finish with out changing the tool.



Evan

[EvanVH]

Thanks allot guys!

These Blacksmiths and Silver & Deming drill bits looks like a very good option. But i probably have to drill atleast one hole first. So that will be a bit time consuming when a shall drilll many holes. But I quess I can`t drill the hole with a boring head directly? (the plate is 5mm thick).

Another option is to buy a R8 end mill holder, and a end mill that can bore horistonal. But this is kind of expensive beacuse I have to buy a R8 holder for each end mill dimension.

So what do you think guys? With option do you think are the best?

Luna is not an option, way to expensive

What about a shell mill (?). They leave some of the material in the center of the hole. Kinda like a hole saw but it will drill through thick material. They are not cheap but will drill a big hole start to finish with out changing the tool.



Evan

[MAS]

If I were you I would use a Hougen Rotabroach cutter (www.hougen.com). They would work good in that chineese iron of your's because they require very little horsepower and drilling thrust. They only cut out the perimeter of the hole and leave a slug that falls out. Your holes would be much more accurate than using a twist drill or end mill.
They have them in metric sizes too. There are many different knock-offs of these cutters nowadays so you shouldn't have difficulty locating one.

Mike

[warrenb]

You don't need a drill bit on a CNC. Simply pocket cut the appropriate hole side.

[Sperstad]

I searched E-Bay, but I didn`t find any shell mill that would work for me, maybee you have a link to me?

I`ve found some Rotabroach cutters at E-Bay, looks very nice! With these I only have to cut one time. But my mill have R8 spindle, what kind of holder do I need? And where do I get it?

You wrote that there was many knock-offs of these Rotabroach kutters, but do they have another name?

[Sperstad]

I`ve found some r8 holders from Hougen, but they are a littlebit expensive. Maybee anyone knows about some other holders?

[Sperstad]

Anyone who can help me with the questions I have above?

[beege]

What material are you trying to cut? How close to 20mm do you need to be? ±1mm? What kind of finish do you need on the inside of the hole? Does it need to be nearly perfectly round? What machinery do you have to perform this operation? How many holes? 5? 1000? 10000?

Answers to these are questions should help others make an educated suggestions. Especially me.

[MichaelHenry]

I`ve found some r8 holders from Hougen, but they are a littlebit expensive. Maybee anyone knows about some other holders?

It would also help if you could say how much you are willing to spend and if you are using a CNC mill or a manual mill.

[MrWild]

If your spindle motor can handle it, drill the first hole about 1/16" undersize, then re-drill to the final size.

Very very wrong advice for large diameter drilling. A pilot hole should be 1.5 times the center diameter of the middle web of the finish drill. i.e. if the finish diameter drill's middle web is 1/8", the the pilot hole should be 3/16", and not over 1/4". When you use drills near the finish size, it allows a chattering entry which can adversely affect the finished hole's size and shape all the way through the part.

[Sperstad]

It`s just regular mild steel I`m working with. The holes need to be pretty close to 20mm, maybee ±0,5mm. Doesn`t need to be a very good finish inside the hole, it`s just holes for some threaded steel bars (the holes shal not be threaded).

I have a manual Industrial Hobbies milling machine, with R8 spindle. Not many holes, about 30 holes in one process.

Some Rotabroach cutters have 19mm shank. Can I just use a R8 collet that have a 19mm collet?

I`m not willing to spend to much money, not more than $100 for a Rotabroach holder.

[Sperstad]

But I quess I could use a holder like this to hold the Rotabroach/annual cutter:

http://cgi.ebay.com/3-4-END-MILL-HOL...em330318412639